


Mystery Machine Mishap!

by Nanenna



Category: Undertale (Video Game)
Genre: Age Regression/De-Aging, Age regressed Sans, Alphys is nervous, Babybones (Undertale), Cuteness overload, Fluff and Humor, Gen, Grillby's regulars also appear, Humor, Papyrus is not prepared, Pre-Undertale, Sans is smol, Undyne is amused, but not enough to be considered a right proper au, no one is really, or five sentry stations anyway, pet the doggies!, poor thing blames herself, so many pets, so very smol, technically an au due to contradicting a few canon conversations, the dogs are in here too, they get pets, they just sit around, this whole thing would be hilarious if she wasn't down five sentries
Language: English
Status: Completed
Published: 2018-02-15
Updated: 2018-02-18
Packaged: 2019-03-19 03:55:00
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 18,992
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13696359
Author URL: https://archiveofourown.org/users/Nanenna/pseuds/Nanenna
Summary: There was an accident at the Lab and now Papyrus is left trying to take care of Sans as a toddler while Alphys tries to figure out what went wrong and how to fix it. To say Papyrus is unprepared is not just an understatement, it's downright fact. But Papyrus is determined to be the best big brother ever, even better than Sans is when he's the older one!





	1. A phone call

**Author's Note:**

  * For [skerb](https://archiveofourown.org/users/skerb/gifts).



> A fun little scenario I've seen a few times (Sans gets turned into a baby/toddler/small child and it's up to Papyrus to take care of him until things go back to normal) but I've only ever seen it in Underfell. I get it, the added danger of having to protect Sans from a dusting as well as watching the usually harsh Fell!Paps trying to care for smol Sans is really nice. But just... just Papyrus having no idea how to take care of a small child sounds like plenty of drama for a story, so here it is! Enjoy as tiny Sans wraps your heart around his pinky phalange!

**Summary for the Chapter:**

> A phone call is made, the mishap is discovered, and Papyrus is left trying to pick up the pieces.

It all started with a phone call from Undyne. She told Papyrus that Alphys had called _her_ to say that something had happened at the Lab and she needed Papyrus to go there right away.

“WOWIE, REALLY? BUT WHY WOULD DR. ALPHYS NEED ME AT THE LAB? I DIDN’T EVEN KNOW SHE KNEW WHO I WAS. WHAT AM I SAYING, OF COURSE SHE KNOWS OF THE GREAT PAPYRUS! BUT STILL… WHY DOES SHE NEED ME?”

“I don’t know,” Undyne replied, “but I’m coming too! I’ll meet you there!” There was a click followed by silence.

Papyrus put his phone away before taking off in a sprint. He was in Snowdin re-calibrating his puzzles when he got the phone call, so he was about as far away from the Lab in Hotland as you could get, but Papyrus would go to any length for a friend in need! Well, for a friend of a friend.

Papyrus slowed to a jog as the Lab came into sight, Undyne standing in front of it wearing causal clothes and sipping from a paper cup. “UNDYNE!” Papyrus called, “DO YOU KNOW WHY DR. ALPHYS CALLED US YET?”

“No, I was waiting for you. Let’s head in.” Undyne chugged the last of her water, then walked confidently into the Lab with Papyrus trailing behind. “Alphys? We’re here!”

“U-up here,” Alphys called from her room.

“YES, WE HAVE INDEED ARRIVED,” Papyrus boisterously called as they walked up the escalator. “AND WE EAGERLY AWAIT YOU TO INFORM US OF WHY WE ARE NEEDED.”

There was a squeal, then the pitter patter of tiny little feet running towards them. “Oh my goodness!” Alphys cried in alarm. “Quick, catch him!”

“daddy!” A tiny skeleton child wearing nothing at all ran straight into Papyrus’s legs and clung to him excitedly. Papyrus and Undyne both looked down at the child in confusion.

“You uh… got something you forgot to tell me about?” Undyne asked with a raised brow.

“I CAN ASSURE YOU THAT I DO NOT HAVE ANY CHILDREN, THERE MUST BE SOME CONFUSION.”

Alphys came huffing towards them with a few pieces of familiar clothes in her arms while Papyrus picked the giggling child up and held them in front of him. “HELLO, LITTLE ONE, WHO ARE YOU?” The child was small, with big, round eye sockets that contained equally big, round, bright pupils, a fixed smile, and short, stubby limbs.

“daddy!” The child squealed again while reaching for Papyrus’s face.

Papyrus obligingly hugged the child close as he turned his attention to Alphys and the clothes in her arms. “WHOSE CHILD IS THIS? AND IS THAT SANS’S HOODIE? IS HE HERE? IS THAT WHY YOU CALLED US?”

“Oh, uh… well y-you see uh… that ch-ch-child is Sans.”

Papyrus and Undyne stared blankly at Alphys while the child in Papyrus’s arms looked up at him in confusion.

“What do you mean this kid _is_ Sans?” Undyne asked as she looked the little skeleton over.

“not daddy!” Sans suddenly wailed, great big tears welled up in his eye sockets and dripped down his face, which was quickly turning red.

“WELL OF COURSE I’M NOT DADDY, SANS,” Papyrus responded in confusion as he held the child out to get a better look at him. Sans squirmed and kicked in his brother’s grasp. “IT’S ME, YOUR BABY BROTHER… THE GREAT PAPYRUS.”

“daaaaaaaaaaddiiiiiiiiieeeeeeeee!” Sans wailed even louder as he kicked and thrashed. Papyrus’s grip started to slip, so Undyne reached over and plucked the squirming child from his grasp.

She expertly hoisted him on her hip and began rocking back and forth as she cooed at Sans. “Shhh… I know… I know… it’s really scary, huh? A bunch of strangers who are talking around you like you aren’t even here. Don’t worry, kid, we aren’t gonna hurt ya.”

“HE DOESN’T RECOGNIZE ME?” Papyrus asked as he turned his attention back to Alphys and wrung his hands in worry.

“He doesn’t recognize anyone, I think he lost his memories when he uh… when the accident… when he got turned into a baby???”

“Hey Sans, how old are you?” Undyne asked as she looked down at the still sobbing but much quieter child. He shyly held up two fingers before hiding his face in her shirt. “Wow, two whole years!” Undyne said in a soft voice as she continued to sway back and forth. “That’s so big!” She turned her attention to Papyrus and Alphys. “So he likely only has the memories he had way back then, right? Paps, how much older is Sans than you?”

“FOUR YEARS OLDER, WHY? OH WAIT… OH...” Papyrus looked down at the still upset toddler. “I WASN’T EVEN BORN YET WHEN HE WAS TWO.”

“So Alph, how did this even happen?”

Alphys started wringing the blue hoodie in her hands, “W-well Sans was helping me with some stuff that was left behind when the previous Royal Scientist uh… left? There were a lot of machines and blueprints and half finished projects left laying around and I was trying to move it all around and uh… o-organize things I guess and Sans was… he was helping me. A-anyway! I found some blueprints and notes that looked like a machine that was actually right there but all the old scientist’s notes are in some kind of code so we were trying to decode it while we were looking over the machine and uh… th-th-then it accidentally activated. W-with Sans ins-s-side.” She gestured helplessly at the toddler. “And uh… he came out like that.”

“ARE YOU SURE THIS LITTLE BABYBONES IS MY BROTHER?” Papyrus asked worriedly.

“Of c-course I’m sure! I Checked him first thing!”

“OH! OF COURSE!” Papyrus turned away to hide a faint dusting of pink on his cheekbones, it was also the perfect opportunity to do a Check of his own. The toddler’s name was indeed Sans, and the description was the same one as always… until a second line was added. Odd, but it still confirmed what Alphys said.

A quiet, muffled, “want daddy,” came from Undyne’s side.

Undyne started rubbing his back, “Yeah, I don’t blame ya kid. But you know what? We got the next best thing, your big brother Papyrus.”

Alphys snorted and Papyrus stared blankly at Undyne, “WHAT?”

“Well, you are bigger than him, aren’t ya?” Undyne hefted Sans higher and angled her body so he was closer to Papyrus. She turned her attention back to Sans, “You love your big brother, right?”

Sans looked Papyrus over shyly. “big bruvvuh?” He asked as he shoved a thumb into his teeth.

“THAT’S RIGHT, YOUR BIG BROTHER THE GREAT PAPYRUS.”

Sans still seemed unsure, but he did at least stop hiding his face in Undyne’s side as he looked Papyrus over more critically. Undyne shifted so Sans was being offered to Papyrus, “Here, take him.”

Papyrus held his arms out and Sans let himself be handed over. Once that was done Undyne expertly shifted Papyrus’s hold until she was satisfied.

“You s-sure seem to know what you’re doing,” Alphys commented.

“Perk of being the head of the Royal Guard, lots of little fans following you around.”

“SO NOW THAT SANS HAS CALMED DOWN, WHAT DO WE DO?”

“W-well, I should be able t-to decipher the blueprints and notes for the machine we were looking at, once that’s done I should be able to figure out what went wrong and h-hopefully reverse this.”

“WELL THAT CERTAINLY IS A RELIEF. I SUPPOSE UNTIL THEN I SHALL HAVE TO BE THE BIGGER BROTHER AND TAKE CARE OF SANS.” Papyrus looked down at the sleepy toddler.

“Yeah! You’re gonna be the best big brother, I can feel it!” Undyne slapped Papyrus’s back unusually gently, he barely had to step forward to keep from toppling over.

“H-here, you should probably have Sans’s th-things.” Alphys offered up the clothes she had been holding, which Papyrus neatly tucked into his inventory save for the hoodie, which was instead carefully wrapped around Sans.

“THANK YOU, DR. ALPHYS. I SHALL TAKE THIS BABYBONES HOME NOW, LET ME KNOW WHEN YOU HAVE REPAIRED THE MYSTERIOUS MACHINE YOU WERE WORKING ON WITH SANS, WHO I DIDN’T EVEN KNOW YOU KNEW.”

* * *

 

The journey back to Snowdin was uneventful, the motion of walking apparently lulling the toddler into a doze. The sound of the door closing must have woke him, as the moment they were inside Sans perked up and looked around. “daddy! daddy we home!” he called at the top of his lungs. Papyrus looked down in surprise while Sans’s head whipped back and forth. “daddy! where daddy?” Sans turned to Papyrus and tugged on his scarf, “pappus, where daddy?”

Papyrus’s mouth opened and closed a few times, his orbits wide and threatening to spill the tears gathered in their corners. “DADDY… ISN’T HOME RIGHT NOW,” he eventually managed to choke out. What he said was technically true: their father wasn’t home at the moment and very likely wouldn’t be. Papyrus tried not to think about it as he carried Sans into the kitchen. “ARE YOU HUNGRY? I HAVE SOME SPAGHETTI I CAN HEAT UP.”

“skeddi!” Sans excitedly squealed, making Papyrus very glad he didn’t have any ears.

Papyrus carefully set Sans down on the edge of the table with his little feet hanging over the edge. “NOW YOU JUST STAY RIGHT THERE WHILE I GET THE SPAGHETTI READY.” Papyrus pulled his freshest container from the fridge and started heating it up. There was a muffled thump followed by giggling fading behind him. He whipped around, the table was empty. He looked down, Sans’s hoodie was a rumpled pile on the floor. He ran into the living room, Sans was waiting for him at the other end of the room and giggled again before taking off diagonally from Papyrus. The taller skeleton quickly darted towards the fleeing toddler and scooped him up. Sans giggled and squirmed while Papyrus sighed in relief and headed back into the kitchen. After some imaginative juggling, Papyrus managed to get a plate of warmed up spaghetti set out on the table and sat himself in a chair with Sans sitting on the table in front of him.

“skeddi!” Sans squealed in delight as Papyrus held a loaded fork up to his mouth. The anticipated pasta barely touched Sans’s teeth before he turned his head and tried to push Papyrus’s hand away. “yucky! no!”

“YUCKY?” Papyrus repeated in shock. “BUT YOU LOVE MY SPAGHETTI!”

“no!” Sans declared again. “yuck! no! no! no!” Sans squirmed out of Papyrus’s hold and crawled to the other side of the table, where he crossed his arms in a huff and refused to look at Papyrus.

After a few more failed attempts to get Sans to eat, Papyrus set the spaghetti aside and rifled through the cabinets. Children were picky, and tastes changed as you got older, so maybe this little version of Sans would rather have something a little simpler than his artisan spaghetti. Aha! Papyrus found the item he was looking for and kept a careful eye on the fussy toddler while he prepped it. Sans kept trying to sneakily glance at Papyrus by twisting his whole body around and quickly looking away with arms crossed whenever Papyrus caught him.

“LOOK SANS,” Papyrus cheerfully said as he moved in front of the pouting toddler and held up a spoon, “DINOSAUR EGGS! DON’T THOSE SOUND YUMMY?” He held up the spoon to Sans’s mouth, but Sans didn’t seem so sure. To prove his point Papyrus stuck the spoon between his own teeth. “MMM… MMMMM… DELICIOUS! IT’S MY FAVORITE! AND IF SOMETHING IS A FAVORITE OF THE GREAT PAPYRUS THEN IT MUST BE YUMMY, RIGHT?” He scooped up another spoonful and held it out to Sans.

Sans cautiously leaned forward and took the bite. The reaction was less extreme than the spaghetti, but his face still scrunched up and he turned his head away. “yucky!”

“SANS, PLEASE! JUST EAT! THE OATMEAL!”

“no! is yucky!” Sans squirmed away from Papyrus, who continued trying to put the spoon in front of Sans’s teeth until Sans slipped from the table and took off running. Papyrus sighed, then put down the bowl and spoon to go give chase.

Once the toddler was captured again, and kicking fussily, Papyrus cheerfully walked back into the kitchen. “THAT’S ALRIGHT, SANS. I KNOW SMALL CHILDREN CAN BE PICKY EATERS. I’M SURE WE HAVE _SOMETHING_ IN THE HOUSE YOU WOULD BE WILLING TO EAT.” A search of the cupboards, the pantry, and the refrigerator belied Papyrus’s optimism. Aside from the box of oatmeal the only food they had in the house were ingredients for spaghetti. Sans’s half of the fridge only had an empty chisps bag, which Papyrus finally just threw away in frustration.

“pappus, hungie.” Sans squirmed in Papyrus’s hold, his face scrunched up and his permanent grin looking strained.

“WELL, YOU CAN EAT MY GOURMET SPAGHETTI OR YOU CAN EAT SOME DINOSAUR EGGS, BECAUSE THAT IS ALL WE HAVE IN THE HOUSE.” Papyrus smiled down at Sans, who only replied by pouting. Papyrus sighed, of course Sans would be difficult no matter his age. “WHAT DO YOU WANT TO EAT, THEN?” Before Sans could answer, Papyrus’s phone started ringing. They both jumped at the loud, jaunty ring tone and Papyrus struggled to pull it out without dropping his brother in the process. “YES, HELLO?” Papyrus answered without even bothering to check the caller ID.

“Hey Paps!” Undyne’s voice erupted from the phone. “Just calling to find out how you and the squirt are doing.”

“WE ARE DOING FINE, REALLY. ASIDE FROM MY BROTHER REFUSING TO EAT, THAT IS. HOW DOES ONE MAKE A FUSSY TODDLER EAT WHEN HE SAYS HE IS HUNGRY BUT REFUSES ALL FORMS OF SUSTENANCE?”

“Refusing to eat, huh? Then he’s not hungry enough!” Undyne yelled.

“W-wait… w-w-what?!” Could be heard faintly in the background.

“Just keep him distracted for a while,” Undyne continued loudly, “and when he’s hungry enough he’ll eat. Don’t let the kid trick you into thinking he needs candy!”

“Undyne, it’s uh… it’s not good to let someone with l-low HP go with-without food. I mean… it’s a-a-actually kinda dangerous.”

“WAIT, WHAT DO YOU MEAN IT’S DANGEROUS?” Papyrus asked in worry as he looked down at the toddler perched on his hip.

Alphys seemed to have taken the phone from Undyne because her voice was much clearer as she explained, “You know how monster food replenishes your HP? Well, if you go too long without eating your HP starts to fall and if you have l-low HP you don’t have far for it to f-fall before um… it gets dangerous.” Papyrus ran a quick Check over Sans.

Sans – ATK 1 DEF 3 HP 19/20  
Your lazy big brother  
who isn’t so big anymore.

Papyrus gasped, “I’M SORRY ALPHYS I HAVE TO GO RIGHT NOW BYE!” Papyrus quickly ended the call and shoved his phone back into his pocket, then turned and ran for the front door. He opened it and stared at the snow, then glanced down at the still naked toddler perched on his hip. Papyrus turned and ran back into the kitchen, picked up the fallen hoodie, wrapped it around Sans again, then ran back to the front door and out it.

“pappus, where we going?”

“WE’RE GOING TO GET YOU SOMETHING TO EAT!” Papyrus slammed open the door to Grillby’s and power walked up to the bar, behind which Grillby was polishing a glass as the regulars lounged in their usual spots.

“……… Papyrus,” Grillby started to say as said skeleton reached the bar and held the toddler up to him.

“GRILLBY FOR SOME WEIRD REASONS SANS REALLY LIKES YOUR GREASY FOOD AND I CAN’T GET HIM TO EAT AND HE’S GOT LOW HP SO NOT EATING IS REALLY DANGEROUS FOR HIM DR. ALPHYS JUST TOLD ME SO AND I’M REALLY WORRIED SO PLEASE CAN YOU JUST FEED HIM SOMETHING PLEASE!”

Grillby’s flames flared up, then darkened to a deep red as he stared at the round faced toddler shoved towards him. “… Papyrus, did Sans have… a child?” Sans was looking up at the fire elemental curiously.

“NO!” Papyrus insisted as he held Sans even closer to Grillby, Sans ducked his head and was trying to hide his face. “THIS IS SANS.”

“…………………………………. what?”

“THIS IS SANS. THERE WAS AN ACCIDENT AT THE LAB WITH DR. ALPHYS AND SANS GOT TURNED INTO A TODDLER AND HE WON’T EAT! DR. ALPHYS SAYS IT’S REALLY DANGEROUS FOR MONSTERS WITH LOW HP TO NOT EAT! AND WHILE HIS HP IS ACTUALLY HIGHER THAN IT’S BEEN IN A LONG TIME, TWENTY IS STILL REALLY, REALLY LOW. AND HE JUST WON’T! EAT! PLEASE, HE LIKES YOUR FOOD!”

Grillby looked down at Sans, who squirmed uncomfortably before shooting him a shy glance. The rest of the bar had gone silent, every last patron staring at the unusual scene with blatant interest. Grillby put a hand on one of Papyrus’s and pushed Sans back towards his brother. “……… have a seat.” Without another word Grillby turned and walked through the fire exit.

Papyrus sat down on one of the bar stools and pulled little Sans into his lap. Next to them Red leaned over to get a better look at the little bundle of bones. “Is that really Sans?”

Sans shyly hid his face in Papyrus’s chest, one orbit angled to peek at the bird monster. “OF COURSE THIS IS SANS,” Papyrus said confidently.

One of the Dogi walked over to Papyrus’s other side and tried to discreetly sniff over Papyrus’s shoulder.

“Can I hold him?” Red asked as they leaned in closer to look at Sans. A couple more of the dog guards moved to crowd around Papyrus and sniff at Sans. The toddler whined and burrowed even further into his brother’s chest, Papyrus adjusted the hoodie to better cover Sans and gently rubbed up and down his spine.

“I DON’T THINK THAT’D BE A GOOD IDEA RIGHT NOW,” Papyrus replied as he began sweating. “MY BROTHER HAS HAD A VERY LONG DAY...”

Grillby returned with a plate piled high with steak cut french fries drizzled in ketchup. He set the plate down in front of Papyrus and then glared at the other patrons until they stopped crowding the skeletons. The smell seemed to be enough to rouse Sans from his hiding spot, once he saw the plate of deep fried potatoes he eagerly grabbed the nearest handful and shoved them into his teeth, getting ketchup all over his hands, face, and Papyrus’s lap.

“SANS, NO!” Papyrus lifted Sans away from the bar top, aghast at the mess that had somehow gotten smeared on either side of the plate. There were titters from around the bar.

“……… I apologize, I don’t have any child friendly food on the menu.”

“Grillby says he doesn’t get a lot of kids in here,” Red supplied as they hid more giggles behind a wing.

Papyrus was taking a napkin to Sans as he eagerly tried to snatch more fries. “THAT IS UNDERSTANDABLE, I’M JUST GLAD THAT SANS IS ACTUALLY EATING.” He settled Sans back in his lap, but pushed the plate out of the toddler’s reach before grabbing a fry and feeding his brother himself. Papyrus managed to work through half the plate, alternating between holding individual fries up to Sans and trying to wipe up the mess Sans somehow made during his brief attempt to feed himself. Now fed, Sans seemed much more alert and kept trying to crawl up onto the bar.

Grillby took the plate away, then came back with a to-go bag. Papyrus started feeling about his pockets for his wallet, while he was distracted Sans finally managed to climb up onto the bar, the hoodie slipping off him in the process.

“I’M SORRY, MR. GRILLBY, I DON’T SEEM TO HAVE MY-” Papyrus looked up to see Sans slowly toddling across the bar towards Grillby, who was blazing bright white and yellow while holding his hands up as if unsure whether to catch Sans or not. Papyrus lunged across the bar and grabbed Sans before he could reach Grillby, then pulled him back. Sans shrieked and started struggling, then just broke down into wailing sobs when Papyrus held him close. “I’M SO SORRY, MR. GRILLBY! I DON’T KNOW WHAT SANS WAS THINKING!”

Grillby tried to speak, but his soft voice was drowned out by Sans’s continued wailing. “It’s okay,” Red cut in. “He’ll just add it to Sans’s tab.”

Grillby nodded and pushed the to-go bag closer to Papyrus, who took the bag and tucked it into his inventory before wrapping Sans up in his hoodie once more. He really would need to find something to actually put Sans in if the toddler was going to keep insisting on running around. Papyrus nodded to Grillby, then cuddled Sans close as he carried the still weeping toddler out of the bar.

Once home, Papyrus looked down at Sans: large tears running down his round cheeks, ketchup and fry grease all over his face and hands, new stains added to the old ones on Sans’s favorite hoodie. Papyrus sighed, a bath was definitely needed, and some sort of clothing that wouldn’t keep falling off. He held Sans close and rubbed his spine gently as he walked up the stairs and into Sans’s room. Papyrus stopped dead and looked around at the usual mess: the trash tornado, the pile of dirty socks, the half made bed… this was no place for a toddler.

“piew!” Sans whined as he looked around the room.

“PEW INDEED!” Papyrs agreed as he turned and walked right back out. “PERHAPS YOU WILL REMEMBER THIS ONCE YOU’RE THE PROPER AGE AGAIN AND WILL ACTUALLY TAKE CARE OF YOUR ROOM.”

Sans sniffled, then rubbed his face against Papyrus’s battle body. Papyrus sighed, it was already covered in toddler tears and ketchup, may as well add brotherly slime to the list. He’d have to properly wash it after all this abuse. Perhaps he would wear something else until Alphys fixed the weird machine that did all this?

He carried Sans into his own room, Sans immediately perked up. His pupils glittered as he took in the bookcase full of children’s books and advanced manuals, the table covered in action figures, the race car bed, just how much cleaner it was. Papyrus opened his closet and started digging through it. Not that any of his clothes would be better sized to fit the toddler, but it was better than trying to dig through Sans’s room. Eventually he found a tank top that he had cropped and modified to say “Good to the Bone” by crossing out “Bad” and writing in “Good” in permanent marker. He held it up to Sans, it would be rather large for a shirt, but the lack of sleeves and short length meant it could be a dress. He also went digging though one of his dresser drawers and eventually came up with a single lime green ribbon and a blue scarf with an orange fish pattern on it. They would have to do.

“YOU READY FOR A BATH, BIG MONSTER?” Papyrus asked Sans, who seemed unsure. Eventually Sans nodded shyly, so Papyrus carried him into the bathroom, carefully shut the door, then deposited Sans on the floor and the clothes on the counter so he could start filling the tub with warm, soapy water. “ALRIGHT SANS, IN YOU GO!”

Once in the water, Sans immediately started giggling and splashing. He was so delighted that he squirmed out of Papyrus’s grasp whenever he tried to clean the toddler. Eventually, after about half the water in the tub got splashed onto Papyrus, the floor, or both, Sans was completely clean. Papyrus pulled him out of the tub, dried him off, then attempted to dress him. Getting the shirt on Sans was actually pretty easy, keeping it from slipping off while Papyrus attempted to make adjustments was harder, especially with an energetic toddler ready to go play squirming in place. Eventually he got the straps of the shirt tied together with the lime green ribbon and the scarf tied around Sans’s middle with a cute bow in the back. It would have to do. Papyrus looked around at the mess in the bathroom, he’d have to clean that up before something got ruined.

“OKAY SANS, YOU CAN GO DOWNSTAIRS AND PLAY WHILE I CLEAN UP THIS MESS YOU UNINTENTIONALLY MADE, OKAY?”

Sans stuck his thumb in his teeth and nodded before turning and running from the room. It took some extra towels, but shortly Papyrus was finished cleaning and carried the pile of soggy towels downstairs to start washing. At the bottom of the stairs his jaw and the towels dropped to the floor in shock, the walls from his knee down were covered in black squiggles. He looked around until he spotted Sans sitting in front of one of the walls, permanent marker in hand.

“SANS!”

The toddler turned around at the shout, another permanent marker rattling around in one of his sockets. Sans’s grin widened, “pappus!”

Papyrus leapt across the room, Sans was up and running faster than Papyrus had ever seen him move in his entire life. There was a moment of vertigo as Papyrus slipped on first one, then the other permanent marker that Sans abandoned when he started running. He turned to find the giggling toddler now on the other side of the living room. “SANS, WILL YOU JUST! STAY STILL FOR ONE MOMENT! PLEASE!” The irony of asking Sans of all people to stay still was not lost on Papyrus, but he was too busy chasing the happily squealing toddler to think about that. Eventually he managed to catch Sans and scoop the giggling, wiggling, squealing toddler up into his arms.

“again!” Sans shrieked in delight as Papyrus held him out at arm’s length.

“NO, SANS, NOT AGAIN. WE DO NOT DRAW ON THE WALLS.”

“pappus! up! up!” Papyrus paused, then held Sans up higher. Sans squealed even more, “again! again!” Papyrus obliged, alternating between lifting Sans up and swinging him low. Eventually Sans’s squeals started to die down and Papyrus placed him on a hip before taking him back upstairs.

“IN THE FUTURE IT WOULD BE BETTER IF YOU DID NOT DRAW ON THE WALLS AGAIN,” Papyrus gently chided as he dug through his drawers for some paper. He returned downstairs and plopped Sans onto the floor with the papers, then grabbed the errant permanent markers and put one in Sans’s left hand. “DRAW ON THE PAPER, OKAY SANS? NOT THE WALLS.”

“okay!” Sans switched the marker to his right hand, then happily started scribbling on the paper.

Papyrus heaved a sigh of relief before grabbing the pile of towels and hurrying to the laundry room. He stuffed them into the washer as quickly as possible, once the load was going he walked back out into the living room and eyed the walls disdainfully. Those would need to be scrubbed before they stained, if it wasn’t too late already. He looked over at the culprit, then froze. The permanent markers and paper were sitting on the floor, but there was no Sans in sight. Papyrus looked around, there was no sign of Sans anywhere in the living room. He was about to go check upstairs when there was a loud crash in the kitchen. Papyrus ran in to find Sans standing in front of an open cupboard with a pile of pots and pans spilling out of it. Sans looked up, a whole potato shoved in his left eye socket.

“WHA…??” Papyrus trailed off, unsure where to even start. “WHERE DID YOU EVEN FIND A POTATO? WE DIDN’T HAVE ANY IN THE HOUSE AN HOUR AGO??” Sans started reaching for the nearest pot, so Papyrus quickly scooped him up again. “WHY DON’T WE GO BACK TO DRAWING?” Sans whined, but otherwise didn’t put up a fight. Papyrus set him down, then gently pried the potato out of his eye socket. “THERE, NOW YOU WILL BE ABLE TO SEE WHAT YOU ARE DRAWING, WHICH WILL VASTLY IMPROVE YOUR ARTISTIC ABILITY.” Papyrus picked up the one paper with scribbles on it and shoved the still blank ones closer to Sans. Then he looked at the drawing, there were three circles with various features on them and oddly angled sticks coming out the bottom. “SANS, WHAT’S THIS?”

“you an’ me an’ daddy,” Sans replied simply as he leaned forward to point at the figures.

Papyrus looked at the picture again, he supposed the tall figure could be him, and the smallest one was very round, but the one Sans said was “daddy” didn’t look like anyone he knew. Papyrus shrugged, it was hard to make out anything from a toddler’s drawing skills, and it wasn’t like Sans had any artistic skills as an adult either. He set the drawing aside and decided to simply sit and watch Sans draw, clean up would have to wait.

As Papyrus knew would eventually happen, Sans began to yawn and have trouble keeping upright. Papyrus scooped him into his arms and carried the toddler upstairs. He paused in front of his door, Sans’s room was still absolutely out of the question for a small child, but that left only Papyrus’s room. With a sigh from Papyrus and another yawn from Sans, Papyrus went into his room and placed Sans on the race car bed. Sans held his arms up expectantly, though Papyrus wasn’t sure what that was about.

“WHAT IS IT, SANS?”

Sans tugged at the makeshift belt around his middle and fussed sleepily with the shirt he was still wearing, “jammies.”

“OH,” Papyrus replied. There was no way anything he owned would be remotely like pajamas on the tiny toddler. He untied the scarf and pulled the shirt off anyway, made much easier by Sans putting his arms up again. “WHAT IF… YOU SLEPT WITHOUT JAMMIES? JUST FOR TONIGHT?” Papyrus tried not to let his nerves show. Sans just shrugged, then sleepily crawled towards the pillows. It was like a light bulb went off above Papyrus’ head, he quickly pulled down the blanket and neatly tucked Sans in, then grabbed one of the books from his shelf and pulled up a chair. “WOULD YOU LIKE A BEDTIME STORY, SANS?”

As backwards as the question felt, Papyrus smiled when Sans sleepily nodded, then happily opened the book and started reading the familiar story. “FLUFFY BUNNY LIVED IN A BEAUTIFUL MEADOW WITH ALL HIS LITTLE BUNNY FRIENDS...”

* * *

It was a little over an hour later and Papyrus was halfway through scrubbing the living room walls when there was a very enthusiastic knock at the door. Papyrus dropped his cleaning supplies and went to answer the door, unsure who would be visiting at this time of night. “OH! UNDYNE! HOW UNEXPECTED OF YOU TO COME VISIT ME SO LATE IN THE EVENING! AND WITHOUT KICKING DOWN MY DOOR!”

“Hey Papyrus!” Undyne greeted. “You gonna let me in?”

“OF COURSE!” Papyrus stepped aside to let Undyne in. Once the door was closed she shoved a box overflowing with stuff at Papyrus, he hesitantly accepted it. “WHY THANK YOU UNDYNE, WHAT IS IT?”

“I figured you needed some stuff for the baby until Alphys can fix this mess. There’s some kid friendly food in there, some toys, some clothes, and whatever else Gerson had on hand he thought you’d need.”

“WOWIE! I’LL HAVE TO GIVE HIM MY THANKS NEXT TIME I SEE HIM, OR SEND THEM ALONG WITH YOU IF I DON’T.”

“Don’t worry, I already gave him your thanks.”

“THANK YOU, UNDYNE! YOU REALLY KNOW HOW TO SAVE TIME.”

“So how’s the little squirt doing anyway?” Undyne eyed the walls that still needed to be scrubbed.

“HE IS CURRENTLY SLEEPING UPSTAIRS. WE HAD A VERY ‘ACTIVE’ AFTERNOON TODAY,” Undyne snorted at the quotes, “AND I MUST SAY I AM VERY GRATEFUL FOR THE BREAK. I NEVER THOUGHT I’D SEE THE DAY WHEN I WAS HAPPY FOR SANS TO TAKE ONE OF HIS LONG NAPS.”

“Yeah, little kids are full of energy like that. And he’s at the age where he should sleep through the whole night, but it’s not a bad idea to check up on him at some point. Sometimes they’ll wake up for a glass of water or something, and the poor kid will probably be disoriented since this is a strange house and all.”

“ACTUALLY, SANS SEEMED TO RECOGNIZE THE HOUSE. WHICH IS REALLY STRANGE, WE DIDN’T MOVE IN UNTIL AFTER THE… UH… UNTIL AFTER I GRADUATED HIGH SCHOOL. BUT WHEN WE WALKED IN THE DOOR HE YELLED ‘DADDY, WE’RE HOME’ AND WAS COMPLETELY COMFORTABLE WITH THE HOUSE.”

“That is weird. Also, speaking of your dad, whatever happened to him? I mean… it’s weird that I hadn’t ever asked before but you never talk about your parents so…?”

“I DON’T REMEMBER OUR DAD VERY WELL, IT WAS JUST SANS AND ME FOR AS LONG AS I CAN REMEMBER. I THINK HE WORKED A LOT? AND WASN’T AROUND MUCH? BUT AT SOME POINT HE WAS JUST GONE??” Papyrus stared down into the box he was still holding with furrowed brows. “I’D ASK SANS, BUT OBVIOUSLY THAT WON’T DO ANY GOOD RIGHT NOW. OH!” Papyrus stepped into the living room and set aside the box before picking up the drawing from earlier and showing it to Undyne. “SANS DREW THIS,” he pointed to each figure as he named them, “THAT’S ME, AND THAT LITTLE ONE IS SANS, AND THIS ONE IS OUR DAD.”

“Heh, that’s pretty good, that one definitely looks like you.” They both looked at it for a moment, then Undyne handed the picture back. “Well, it’s something to ask Sans when Alphys fixes him. Along with a bunch of other questions like how he and Alphys even know each other.”

“I HAD BEEN WONDERING ABOUT THAT TOO, PERHAPS WE SHOULD JUST ASK ALPHYS TO ANSWER THOSE QUESTIONS SINCE SHE WOULD ACTUALLY KNOW THE ANSWERS.”

“Yeah, I’ll ask her later, but that doesn’t stop me from wanting to hear what Sans will say. Or what he won’t say.”

“SANS DOES LOVE HIS POINTLESS SECRETS,” Papyrus agreed.

“Welp, I’m going to head home. Early to bed and all that, but Gerson said to just pop by Waterfall any time and visit him if you need any help. Or even if you don’t. He wants to see Sans as a ‘little whippersnapper’ before this mess gets all cleared up.”

“I’LL MAKE SURE TO GO VISIT HIM THEN. HAVE A GOOD NIGHT, UNDYNE.”

“You too!”


	2. Getting Prepared to be Prepared

**Summary for the Chapter:**

> The townsfolk are curious, the skelebro house is still not child proofed, and Papyrus still has almost nothing for taking care of a toddler, but at least that last one gets fixed.

The next morning started even earlier than normal. Just as Papyrus was starting to think about what to make for breakfast, he heard a knocking sound from upstairs followed by little Sans’s plaintive voice. He ran up the stairs to find the toddler standing at the end of the hallway, knocking on the wall.

“daddy! daddy get up!” Sans called at the wall.

“SANS, WHAT ARE YOU…? SANS?”

Sans turned and pointed at the wall, “where daddy? daddy door gone!”

“DADDY ISN’T HOME RIGHT NOW,” Papyrus said carefully. “ARE YOU HUNGRY? I WAS ABOUT TO GO MAKE BREAKFAST, OR YOU COULD FINISH OFF THE FRIES FROM GRILLBY’S.” Papyrus flinched as he offered the fries, but since he wasn’t sure Sans would eat what Undyne had brought over he thought they would be better than nothing.

Sans rubbed an eye socket, then trundled towards Papyrus with his arms up. “hungy.”

Papyrus scooped Sans up, then carried him downstairs. One of the things Gerson had sent over was a kind of booster seat with a belt attached, something that Sans would at the very least have a hard time getting out of. Once he got Sans settled in Papyrus reminded himself he really would need to go thank Gerson in person. He bustled about the kitchen pulling options out, when he turned back to Sans he found the toddler still sitting in place and couldn’t help the relieved grin that spread across his face.

Breakfast turned out to be almost as messy an affair as dinner the night before, but since Papyrus hadn’t dressed Sans yet the clean up would be relatively easy, just wiping down his bones with a damp cloth. Once that was taken of Papyrus dressed Sans in the outfit Gerson had sent over: a green and pink striped shirt, a pair of little overalls, yellow socks, and a pair of shoes that were way too big and were eventually just left off.

“THERE, YOU LOOK SO MUCH BETTER IN CLOTHES THAT ARE ACTUALLY MEANT FOR A MONSTER OF YOUR DIMINUTIVE STATURE!” Sans fiddled with the straps of his overalls, seemingly entranced by the feel of the buttons. “NOW SANS, WE ARE GOING TO GO TO THE SHOP AND SEE ABOUT GETTING YOU A FEW MORE THINGS, LIKE SHOES THAT ACTUALLY FIT. YOU READY TO GO?”

“okay,” Sans held his arms up. Papyrus picked Sans up and settled him on a hip, then did one last check to make sure he had everything he needed. Papyrus’s phone started ringing. He pulled it out to see the caller was an unknown number.

“HELLO?”

“S-so I was just calling to l-let you know… um… I mean! Alphys here! I uh… asked Undyne for your number, I hope you don’t m-mind.”

“HELLO DR. ALPHYS,” Papyrus said cheerfully. “HOW ARE YOU THIS MORNING?”

“I’m f-fine, thanks for asking. Oh! How is Sans is he still uh… tiny?”

“SANS IS FINE AS WELL, NO CHANGES FROM LAST NIGHT THOUGH.”

“R-right, I suppose it w-was too much to hope it would wear off after a g-g-good night’s sleep. Anyway, I called to let you know that I won’t be working on the machine r-right away. I want to finish decoding th-the blueprints and notes first, t-t-to make sure there are no more accidents like with Sans. But uh… S-Sans was the one doing most of the decoding so… it might take me a while...” Alphys trailed off sadly. Just as Papyrus was about to assure her it would be fine, she picked back up. “B-but don’t worry! I’m sure I can figure this out and fix the machine and restore Sans! It might take a while, but I will do it! Okay?”

“THAT’S WONDERFUL, DR. ALPHYS. I HAVE EVERY FAITH IN YOUR ABILITIES! AFTER ALL, ANYONE WHO CAN BUILD AN AMAZING ENTERTAINMENT ROBOT LIKE METTATON WILL SURELY BE ABLE TO FIGURE OUT AND REPAIR SOME OLD MACHINE THAT CAN MYSTERIOUSLY TURN MONSTERS BACK INTO SMALL CHILDREN.”

“R-right...” Alphys didn’t sound so sure of herself.

“AND OF COURSE, IF THERE IS ANYTHING THE GREAT PAPYRUS CAN DO TO HELP YOU WOULD ASK, BECAUSE I WOULD BE MORE THAN HAPPY TO HELP IN ANY WAY I CAN.”

“About th-the uh… about the only way to help right n-n-now would be to help decode the… the notes. Are you uh… do you happen to know the cipher? Like Sans did?”

“I DID NOT EVEN KNOW SANS KNEW ANY CIPHERS OR CODES, MORE OF HIS POINTLESS SECRETS. NO, NOT YOU SANS. OLDER SANS… I KNOW IT’S WEIRD AND CONFUSING. I’M SORRY ALPHYS, I THINK I NEED TO LET YOU GO, LITTLE SANS IS GETTING CRANKY.”

“Maybe he needs a nap?” Alphys asked, unsure if toddlers took naps in the middle of the morning.

“OH, IMAGINE THAT. SANS NEEDS A NAP.”

Alphys snorted, the hand not holding the phone slapped over her mouth to muffle the inelegant sound. “W-well I’ll let you go and uh… get back to work I guess. T-talk to you later, Papyrus.”

Sans tugged on Papyrus’s shirt and asked for the phone. “JUST A MOMENT BEFORE YOU HANG UP, SANS HAS SOMETHING TO SAY.” Papyrus held the phone up to the toddler.

Sans brought the phone close and whispered, “bye bye, i love you,” into it before pushing it back towards Papyrus. There was a high pitched shriek and a puff of smoke from the phone, followed by a click. When Papyrus checked the call was ended and the phone seemed unharmed despite the odd smoke it had just emitted.

Papyrus shrugged and pocketed the phone before turning his attention back to Sans. “NOW, ARE YOU READY TO GO TO THE STORE WITH ME FOR REAL THIS TIME ASSUMING THERE ARE NO MORE INTERRUPTIONS?”

“yeah,” Sans replied as he grinned up at Papyrus.

“THEN LET US GO TO THE STORE, NYEH HEH HEH!” Papyrus pointed dramatically before leaving the house and excitedly running down the street.

The bell over the door jingled when Papyrus entered, he knocked the snow from his boots before going inside and carefully shut the door behind him. “Well hello there, Papyrus.” Bonnie smiled at the tall skeleton, “I heard a rumor and was hoping you could clear it up for me.” Her eyes traveled down to the toddler perched on Papyrus’s hip and her ears perked up.

“HELLO BONNIE,” Papyrus cheerfully greeted the shop keep. “I DON’T KNOW WHAT RUMOR YOU MAY HAVE HEARD, BUT I DO KNOW THAT SANS HERE WAS TURNED INTO A TODDLER BY ACCIDENT AND HE IS IN NEED OF SOME SUPPLIES.”

Bonnie whistled, “That was the rumor I was talking about. Goodness, well ain’t that just something else.” She leaned over the counter to get a better look at the toddler. “Well hey there, sweetie, remember me?”

Sans shyly waved at Bonnie, but otherwise kept his face hidden in Papyrus’s side. “HE DOESN’T SEEM TO HAVE HIS MEMORIES OF BEING OLDER,” Papyrus explained quietly. “AND IS VERY SHY.”

“That’s okay, all my little nieces and nephews were shy at that age too, I understand. So how can I help you?”

“I WAS HOPING TO PURCHASE SOME SUPPLIES FOR SANS, WE’RE NOT SURE WHEN DR. ALPHYS CAN FIX ALL THIS SO I’M JUST STOCKING UP FOR NOW. THE GREAT PAPYRUS IS GOING TO BE PREPARED FOR ANYTHING! NYEH HEH HEH!”

“heh heh heh!” Sans echoed from Papyrus’s side with a wide grin on his face.

“SO DO YOU HAVE ANY CLOTHES IN HIS SIZE?” Papyrus continued. “OR FOOD HE MIGHT LIKE? GERSON SENT OVER SOME THINGS BUT IT WAS A STOPGAP MEASURE AT BEST.”

“Hm… can’t say I have much,” Bonnie admitted. “But I’ll tell you what, my sister might have some spare things she can send over, I’ll tell her to stop by later.”

“THANK YOU, BONNIE, THAT WOULD BE VERY HELPFUL. TODDLERS NEED A SURPRISING AMOUNT OF CARE, I HAVE FOUND.”

Bonnie just nodded. Sans tugged at Papyrus’s shirt, “cinny bunny!”

“NOW SANS, YOU JUST ATE! YOU DON’T NEED ANY SWEETS.”

“Awww… let him have it,” Bonnie wheedled. “At that age they stop eating when they’re full, and he’s been such a good little monster, haven't you Sans?” Bonnie smiled wider as she pulled out a cinnamon bunny and held it out for Sans. Before Papyrus could say anything else, Sans had snatched the treat and shoved it in his mouth.

“SANS! SUCH MANNERS! WHAT DO WE SAY TO NICE MONSTERS WHEN THEY GIVE US NICE THINGS?”

Sans looked up at Bonnie and grinned all the wider, crumbs and icing all over his face. “aye wuv yuu.”

“Oh my goodness!” Bonnie put a hand over her chest as if she had just been shot. “I… I love you too, Sans.” The toddler grinned before cramming more of the pastry into his mouth.

“SANS! YOU WERE SUPPOSED TO SAY ‘THANK YOU’ TO BONNIE!”

“That’s alright, I think he’s just fine as is. I’ll just...” Bonnie held up a finger, then quickly gathered more cinnamon bunnies into a paper bag and handed them over to Papyrus. “Just to make sure you have a treat for such a well behaved little monster.” She winked at Sans.

“WELL… THANK YOU, BONNIE, THAT’S VERY SWEET OF YOU.” Papyrus accepted the bag with a grin. The pair waved before exiting the store.

Papyrus was feeling much better, between the boxes of cold cereal Gerson had sent over, the fries from Grillby’s, and the cinnamon bunnies from Bonnie, he was sure Sans wouldn't go hungry at least. As they approached the house, Papyrus was surprised to see Grillby standing on the porch. He had just turned away from the door when Papyrus raised a hand in greeting.

Before either of them could say a thing, Sans shrieked, “girby!” and started squirming in Papyrus’s hold.

“HELLO, MR. GRILLBY, WHAT ARE YOU DOING AT OUR HOUSE? CAN I HELP YOU?” The closer Papyrus got to Grillby, the harder Sans squirmed. Once Papyrus was on the porch it became a struggle to keep the toddler contained. Papyrus quickly tucked the bag of pastries into his inventory to free up his other hand.

“girby!”

“…… actually, I want to help you.” Grillby held up one of the ‘to-go’ paper bags from his restaurant along with a fresh bottle of ketchup.

“girby! girby!”

“OH! THANK YOU!” Papyrus had no intention of feeding Sans any more of Grillby’s greasy food if he could help it, but considering how picky Sans had been so far it wouldn’t hurt to keep his options open. As Papyrus reached to accept the offered food, Sans finally managed to squirm out of his grasp and plopped onto the porch. Before either adult could react, Sans had attached himself to Grillby’s leg.

“girby!” Sans declared happily as he buried his face into the elemental’s knee.

“…………………” Grillby stared down at the toddler, unsure what to do.

“WOWIE! I DIDN’T THINK SANS REMEMBERED ANYTHING FROM BEING OLDER, BUT I THINK HE REMEMBERS WHAT GOOD PLATONIC FRIENDS YOU TWO ARE!”

Grillby just nodded as Papyrus tucked the bag of fries into his inventory. Unsure what else to do, Grillby awkwardly patted Sans’s skull. Sans looked up at him, all smiles.

“THAT’S VERY SWEET OF YOU SANS, BUT I’M SURE MR. GRILLBY HAS A VERY BUSY DAY AHEAD OF HIM AND YOU NEED TO LET GO OF HIM SO HE CAN GO.”

“noooooooooooo...” Sans whined and clung to Grillby’s leg all the harder.

“SANS, NOW IS NOT THE TIME FOR YOUR USUAL STUBBORN TENDENCIES!” He grabbed Sans and bodily dragged him away from Grillby. Sans immediately started crying. Big, globby tears trailed down his chubby cheek bones as Papyrus settled the toddler in his arms. Sans leaned towards Grillby and reached for him as he continued to cry. “I’M SORRY ABOUT THIS, MR. GRILLBY. SANS HAS BEEN VERY EMOTIONAL EVER SINCE THE ACCIDENT.”

“……… that’s quite alright, children cannot help being emotional.” Grillby gently pet Sans’s skull again, causing the toddler to calm down a little. “…… I should get going, I will need to open soon.”

“GOODBYE, MR. GRILLBY.” Sans’s crying picked back up as Grillby left. “REALLY SANS, IT’S NOT AS IF YOU WILL NEVER SEE HIM AGAIN.” Papyrus took Sans inside and set about rocking and soothing him until the toddler calmed down. He had just gotten Sans distracted with a bright orange plush dinosaur Gerson had given him when there was a knock on the door. Papyrus set Sans down and the couch and went to answer it. “HELLO MS. RUBY, I’M VERY GLAD TO SEE YOU!”

“Hello Papyrus,” the innkeeper replied. Little Usa stared up at him from behind her mother’s skirt. “Bonnie told me you need some things for Sans while he’s uh… small? Oh! Is that him?”

Papyrus looked down to see Sans was looking at Usa and Ruby from behind his legs the same way Usa was looking at them from behind her mother. “YES, AS YOU CAN SEE SANS IS NOW EVEN SMALLER THAN BEFORE, AND HE WAS VERY SMALL TO BEGIN WITH.”

Ruby giggled, “Well I do have a few things, I hope they help.” She held up a cardboard box, which Papyrus accepted gratefully.

“THANK YOU, I’M SURE THIS WILL BE A GREAT HELP IN TAKING CARE OF SANS UNTIL DR. ALPHYS CAN FIX EVERYTHING.” He peeked into the box to see it was full of small clothes, a few pairs of little shoes, and a couple toys.

“Of course, it can be so hard being a single parent. Not that I would know personally, but even with a spouse children are a lot of work. Can’t take your eyes off them for a second.”

“THAT IS A LESSON I LEARNED ALL TOO WELL JUST YESTERDAY,” Papyrus sighed as he remembered the antics Sans had gotten up to the night before.

“Well I’ve got to get back to the inn, there’s only so long Bonnie can cover for me. Come along, Usa! Say goodbye to Mister Papyrus and Sans.” Ruby and Usa waved before they turned to leave, walking down the street hand in hand.

Papyrus shut the door behind them, then turned to face Sans. “HOW ABOUT WE SEE IF ANY OF THESE SHOES FIT, THEN WE CAN PLAY IN THE SNOW!” Sans was excited about the idea of playing in the snow and squirmed in place as Papyrus tried the shoes on him. The second pair fit well enough, and he had just gotten the first one securely tied when there was another knock at the door. “JUST A MOMENT!” Papyrus called, he didn’t want Sans running around with just one shoe on, he’d be sure to fall if he tried walking that way, so he quickly tied the other before going to answer the door. This time Sans trailed behind him and hid behind the taller skeleton’s legs as Papyrus opened the door. “OH! HELLO MS. SYLVILA! I WAS NOT EXPECTING YOU TO STOP BY TOO.”

“Hello Papyrus,” a white rabbit monster greeted. “I heard from Dizzy what happened at Grillby’s yesterday, and Bonnie confirmed it wasn’t just some silly rumor. She also said you could use some things for Sans?” She held up an armful of clothes. “Cinnamon just outgrew a few things and I was wondering what to do with them.”

“OH YES, I’M VERY GRATEFUL FOR ANY SUPPLIES FOR SANS, WE’RE NOT SURE HOW LONG HE’S GOING TO BE STUCK AS A TODDLER AND IT WAS A MOST UNEXPECTED TURN OF EVENTS.” Papyrus accepted the offered pile, an awkward affair of somehow getting his arms underneath it as Sylvila moved her own arms out of the way. “AND I AM CERTAINLY GLAD THAT EVERYONE HAS BEEN SO HELPFUL SO FAR!”

“Of course, dear! As you said, it’s so unexpected after all! Nobody could be prepared for their big brother to suddenly get turned into a small child. How have you been holding up?”

“THE GREAT PAPYRUS HAS BEEN DOING AN EXCELLENT JOB! SANS HAS BEEN KEPT FED, ENTERTAINED, AND EVEN GOTTEN MORE EXERCISE IN THE LAST DAY THAN I’VE SEEN HIM GET IN A YEAR!”

Sylvila giggled, “Yes, toddlers certainly are full of energy. Don’t forget to lay him down for a nap later, they often fight it but they do need the rest.”

“I’M SURE SANS WILL BE EXCITED TO TAKE A NAP,” Papyrus said confidently.

“It was nice chatting with you, but I’ve got to get going. There’s no knowing when Paprika and Cinnamon will get back from one of their slow walks.”

“THANK YOU AGAIN!” Papyrus called as Sylvila left. He had just deposited the fresh pile of clothes on top of the half filled box Ruby had given him when there was another knock at the door. Sans trailed after Papyrus again as he went to answer the door, “OH, HELLO MR. PAUL!”

A large, brown bear monster in an orange jacket stood in the doorway holding a casserole dish filled with… something. “Hello Papyrus, I heard an interesting rumor and thought you could use a warm meal.”

“WHY THANK YOU, THAT’S VERY KIND OF YOU.”

“Oh!” Paul froze in the middle of handing the dish over to Papyrus to stare down at Sans. “Is that really Sans?” He unceremoniously shoved the dish at Papyrus and crouched down to get a better look at Sans.

“YES, THAT REALLY AND TRULY IS SANS, HE’S VERY SHY.”

“I can see that,” Paul replied as he tried to get a better look at the toddler hiding behind Papyrus’s boots. When he tried to reach for Sans, causing the toddler to flinch and shrink further back, Papyrus decided they had both had enough.

“WELL THANK YOU FOR THE UM… THE DISH. IT WAS VERY THOUGHTFUL OF YOU, I’M SURE. BUT WE HAVE A BUSY DAY AHEAD OF US AND REALLY MUST GET BACK TO IT.”

“Certainly, gotta keep them political gears grinding.” Paul waved a farewell before turning away as Papyrus shut the door.

Papyrus heaved a sigh of relief before going into the kitchen to find someplace to stash the dish. The rest of the morning went on like that, more of the townsfolk stopping by with second-hand clothes and toys to gift Sans, more advice on childcare, a few with food that Papyrus wasn’t all that sure would appeal to Sans, and a few who were just curious and wanted the rumors running around town confirmed. Papyrus found the attention strangely exhausting, why would their well meaning neighbors kindly gifts tire him out so? Perhaps Papyrus was just exhausted from the whole situation.

“pappus,” Sans grabbed one of Papyrus’s fingers and tugged insistently, “hungy.”

“OH GOODNESS, WHAT TIME IS IT?” Papyrus found the clock and realized the whole morning had gotten away from them. “WOWIE, NO WONDER! WELL, WE HAVE A LOT TO CHOOSE FROM, HOW ABOUT WE BOTH GET SOME LUNCH?”

* * *

Papyrus was wiping a bit of spilled food from Sans’s face as the toddler sleepily nodded his head. Papyrus couldn't help but smile at that, of course Sans would need a nap. Honestly, Sans’s napping habits were already very toddler-like, this at least hadn’t changed. Papyrus scooped Sans up and carried him upstairs, then tucked him into the race car bed.

Sans sleepily rubbed an orbit and yawned. “not sleepy,” he insisted.

“I AM NOT SO SURE I BELIEVE THAT,” Papyrus said with repressed laughter as he watched Sans snuggle into the bed and start to drift off. He was sorely tempted to take a nap himself, and he was starting to wonder why he was resisting. After all, he had been told by five different monsters that he needed to take care of himself as well, a short nap would do him good. So Papyrus laid down on the bed next to Sans and drifted off.

Papyrus woke with a jump, something had startled him awake and he was groggily trying to figure out what. He blearily looked around, he had been asleep on top of his covers, which was odd. But even odder was the way the corner of them were thrown back.

Where was Sans?

The realization that he had fallen asleep next to Sans but Sans was now not in the bed woke Papyrus the rest of the way up. He jumped out of bed and ran from the room. There was a loud voice coming from downstairs, he ran down them to find Undyne standing in his living room with a giggling Sans held up above her head. Papyrus sagged against the stair rail in relief.

“UNDYNE, WHEN’D YOU GET HERE?”

“Just now! Hey! What was Sans doing sitting in the living room all alone?”

“THE SLIPPERY LITTLE SNAIL SNUCK OUT OF THE ROOM WHILE I UH… WHILE I WASN’T LOOKING!”

“Yeeeaaaaah,” Undyne eyed him like she wasn’t quite sure she believed the whole story, causing Papyrus to sweat nervously. “Little kids are sneaky like that. Good thing Aunty Undyne is here to keep this little punk out of trouble!” She lifted him in the air again, causing Sans to squeal in delight.

“AUNTY UNDYNE?” Papyrus asked as he stepped the rest of the way into the living.

“Yeah, just until this little squirt isn’t quite so little anymore. Hey! I noticed you’ve been busy.” Undyne shifted Sans to her hip so she had a hand free to motion to the piles of toys and toddler sized clothes sitting around the living room.

“OH YES, EVERYONE HAS BEEN VERY KIND AND GENEROUSLY GIVING SUPPLIES FOR SANS. MOST OF THESE ARE CLOTHES OTHER CHILDREN HAVE RECENTLY OUTGROWN, BUT A LOT OF IT FITS SURPRISINGLY WELL.”

“That really is nice, it’s good to see monsters coming together to help each other out!”

“AND YOU SHOULD SEE THE PANTRY AND REFRIGERATOR! IT SEEMS EVERYONE DECIDED TO HELP WITH SANS’S PICKY EATING HABITS BY GIVING HIM LOTS OF OPTIONS. THOUGH I’M NOT SURE HALF OF THEM ARE THINGS A TODDLER WOULD LIKE TO EAT.”

“Papyrus, you goof! I’m sure some of it’s meant for you too!” Undyne laughed.

“OH, RIGHT. OF COURSE. THE GREAT PAPYRUS KNEW THAT.” He looked away to hide the faint dusting of pink that washed across his cheek bones.

“pappus! pappus!” Sans was reaching for Papyrus, who happily took the toddler from Undyne’s grasp. “up! up!”

“REALLY? AND HERE I THOUGHT YOU WOULD RATHER LAY BACK DOWN,” Papyrus teased as he lifted Sans into the air again.

Undyne smiled, “I was right, you really are a good big brother.”

“OF COURSE I AM, NYEH HEH HEH! BUT THANK YOU FOR THE COMPLIMENT ANYWAY.”

**Notes for the Chapter:**

> I don't know why I started adding in all that mystery with their father, but I trust everyone in this fandom to realize who he was and what's going on. But I'll spell it out anyway because I'm a dork like that: it's Gaster. Their father was Gaster. And no, the mystery is not solved in this fic, that was never the point. It's just some angst that kept inserting itself in that wouldn't let me cut it. Gotta have some I guess, gotta balance out the toddlery adorableness somehow!
> 
> Also the bit with Sans saying "i love you" instead of "thank you" is based on something that actually happened to me while i was working at an ice cream shop. It was so adorable I wanted to give the kid another ice cream! And of course, I couldn't help putting in hints of my OTP. But since half of my OTP is a toddler right now there's not exactly any good way to put in content for my OTP so it's just hints. Feel free to ignore if they're not your OTP.


	3. A New Routine

**Summary for the Chapter:**

> Life settles into a new routine... one which Papyrus immediately disrupts! There's a lot of snow, some doggerly scolding, some fisherly scolding, and then a puppy gets some pets.

Nearly a week had gone by. Papyrus found that his days fell into a rhythm as he cared for his little big brother. He couldn’t help but feel forgotten by Alphys, she hadn’t called since that first day, she barely updated her Undernet profile anymore, and even Undyne hadn’t heard much from the reclusive scientist. Papyrus wanted to take it as a good sign, that it meant Alphys was working hard on fixing the machine and getting Sans back to normal. But at the same time he would have liked to hear from her. So after laying Sans down for his afternoon nap, Papyrus pulled up the doctor’s contact info and started a call.

“H-hello?”

“HELLO, DR. ALPHYS!”

“Oh! P-Papyrus! What are you… why are you… what’s g-going on?”

“I WANTED TO FIND OUT HOW YOU ARE DOING. UNDYNE TELLS ME YOU SOMETIMES FORGET TO TAKE CARE OF YOURSELF AND I WANTED TO MAKE SURE YOU WERE EATING AND RESTING REGULARLY.”

“Oh, um… it’s fine. I’m fine, Undyne has been over often to make sure I uh… don’t get lost in my work?? She really wants to help me as much as she can, she says with both you and Sans uh… out of commission th-that the sentry stations are really falling apart.”

“OH DEAR, I WAS SO BUSY TAKING CARE OF SANS THAT I DIDN’T EVEN THINK ABOUT HOW MANY SENTRY STATIONS WERE GOING UNMANNED!”

“Y-yeah, I don’t think Undyne has replacements for you either. She wants you both to have jobs waiting for you when uh… when I eventually m-m-manage to fix things.”

“THAT IS THE OTHER REASON I WAS CALLING, I WAS HOPING YOU WOULD TELL ME HOW THINGS ARE GOING. HAVE YOU FINISHED DECIPHERING THE NOTES? HOW BADLY IS THE MACHINE BROKEN?”

“I’ve uh… I’m almost halfway through the notes! I had to use the other blueprints and notes that Sans had already deciphered for me to try and make a cipher for these notes. At first it seemed like it was just a straight one for one alphabet replacement and would be fairly simple, but not all of the translations Sans has written out match up. I was starting to wonder if there were some shifting going on, some sort of extra key I’d need but don’t have, but when I applied the cipher I had first developed to the already translated notes I realized that Sans was summarizing a lot of this stuff, so my cipher actually works! It’s going faster now that I’ve figured that out, the only hard part is just how messy the handwriting is. Whoever wrote all this down has just the worst handwriting!”

“SO NOW THAT YOU HAVE A CIPHER, THINGS WILL MOVE QUICKER? HOW MUCH LONGER DO YOU THINK IT WILL TAKE?”

“Oh, w-well… like I said the handwriting is very m-messy so I have to keep going back and correcting my translations, w-which means my translations are g-getting messy too and uh… even after I finish t-translating all these I still have to start work on the machine itself so uh… it might take a w-while yet.”

“THAT IS FINE, I WOULD RATHER YOU TAKE THINGS SLOW AND GET IT RIGHT THAN TO RUSH AND HAVE AN ACCIDENT YOURSELF!”

“Y-yeah, that’d be just… just awful!” Alphys laughed nervously.

“WELL THANK YOU FOR YOUR TIME, DR. ALPHYS. GOOD LUCK!”

“Oh! Okay then, g-good luck to you too! With uh… with little Sans that is. I m-mean, I’m sure you’re taking great c-care of him. And uh… okaygottagohaveagooddaybye!”

There was a faint click as the call abruptly ended, then Papyrus scrolled through his contacts. He hadn’t put much thought into what he was about to do, but it just felt right. Papyrus hit the call button.

“Hey dork!” Undyne’s voice greeted him.

“HELLO UNDYNE!”

“So what’s going on, the little squirt doing okay?”

“OH SANS IS FINE, HE’S DOWN FOR A NAP RIGHT NOW. I WAS JUST TALKING TO DR. ALPHYS AND SHE REMINDED ME THAT I HAVE BEEN TERRIBLY NEGLECTFUL OF MY DUTIES EVER SINCE THE ACCIDENT.”

“Well yeah, you have a baby to take care of. A literal baby! That’s a lot of work!”

“A TODDLER, BUT THAT IS NO EXCUSE TO NEGLECT MY DUTIES AS A SENTRY! SO TOMORROW I’M GOING TO RESUME MY DUTIES. I’M AFRAID THERE IS NOT MUCH WE CAN DO ABOUT SANS, BUT I CAN AT LEAST RE-CALIBRATE MY PUZZLES, DO MY PATROLS, AND WATCH OUT FOR HUMANS LIKE I’M SUPPOSED TO!”

“Well, if you’re sure...”

“DON’T WORRY, I HAVE EVERYTHING UNDER CONTROL! NYEH HEH HEH!” Papyrus hit the end call button, then decided to go upstairs and check on Sans. When he got to the top of the stairs his eye sockets were drawn to the end of the hallway where Sans was staring up at the blank wall, one elbow up which probably meant his thumb was in his mouth again, and a bright orange dinosaur plush toy dragging limply from his other hand. “SANS? WHAT ARE YOU DOING OVER THERE?”

Sans turned around at Papyrus’s voice, then slowly toddled over to the taller skeleton and raised his arms to be picked up. Papyrus obligingly picked Sans up and cuddled him close. “WHAT IS IT, BROTHER?”

“i miss daddy.” Sans sniffled as he clung to Papyrus, “where daddy?”

“DADDY IS…” Papyrus hesitated, unsure what exactly to tell Sans, “DADDY IS AWAY. RIGHT NOW.” There, that was close enough to the truth. He didn’t want to outright lie to Sans, but he also had no idea how to tell the toddler that he had no idea where their father was or even if he was still alive at all. Papyrus couldn’t remember it, but he was fairly certain their father had Fallen Down a long time ago. He sighed as he rocked the clinging toddler. “I’M SURE HE MISSES YOU AS MUCH AS YOU MISS HIM.”

Sans made an indistinct noise as he buried his face into Papyrus’s shoulder. Well, the only thing to do was to distract him. “WHY DON’T WE GET SOME STURDY CLOTHES ON AND GO OUTSIDE TO PLAY IN THE SNOW? WE CAN BUILD A SNOWMAN!” Papyrus suggested enthusiastically.

Sans gave a small nod, he did like building snowmen with Papyrus.

* * *

The next day, after breakfast was finished and the dishes were washed and put away, Papyrus dressed Sans in the warmest clothes they had. Papyrus knew it didn’t really matter, that Sans wouldn’t even feel the cold, but it made him feel better anyway. Papyrus also pulled out one of the things Gerson had sent over: a toddler leash. Papyrus hadn’t felt the need for it yet, he had stayed pretty close to Sans so far or carried the toddler whenever they went somewhere far. But while he was on patrol and re-calibrating his puzzles… Papyrus attached it to Sans, then clipped the other end to his belt.

“TODAY, SANS, WE ARE FINALLY GOING BACK TO WORK. I WILL RE-CALIBRATE ALL OF OUR PUZZLES! AND WE WILL GO ON PATROL! AND WE WILL BE PRODUCTIVE! TOGETHER!”

“yay!” Sans cheered, and Papyrus was so happy to see Sans be enthusiastic about work for once!

“LET’S GO!” Papyrus took Sans outside and they set off. Papyrus knew they had a lot of ground to cover, so he was striding along at his usual, speedy pace.

“pappus! pappus wait!” Sans’s little legs couldn’t keep up. He tried running after Papyrus, tripped, and fell flat on his face.

Papyrus stopped and went back to pick him up, but Sans was already sniffling and whining about the snow in his orbits and nasal cavity. “NOW, NOW, YOU’RE SUCH A BIG MONSTER! NO NEED TO CRY!” Papyrus gently brushed the snow from his brother’s face, then picked Sans up. “WHY DON’T I CARRY YOU TO THE PUZZLES, THEN WE CAN RE-CALIBRATE THEM TOGETHER!” Sans simply nodded as he snuggled into his brother’s arms.

As Papyrus continued to walk Sans perked up and began looking around in interest, he hadn’t been brought past the ‘Welcome to Snowdin’ sign. Not since the accident, anyway. The scenery quickly became boring, just more of the same snow and trees as the town without interesting buildings to break it up. Sans settled into Papyrus’s arms and let himself be carried. Soon they came to the first puzzle, the slippery Xs and Os one. Re-calibrating it was always a challenge for Papyrus, even without a toddler along for the ride, but Papyrus refused to be defeated. He deftly skated across the ice with Sans in one arm and soon had it calibrated perfectly.

“THERE, SEE? I KNEW WE COULD DO IT!”

“’m bored,” Sans whined.

“WELL THAT'S BECAUSE YOU COULD NOT HELP WITH THIS PUZZLE. I AM SURE THE NEXT ONE WILL BE FAR MORE ENTERTAINING. IN FACT, AFTER I RE-CALIBRATE IT YOU SHOULD TRY SOLVING IT!”

Sans nodded, unsure how exciting that really would be.

Papyrus easily stepped over the spikes to the next puzzle and set Sans down. He started working on the puzzle, leaving Sans to his own devices. The toddler ran back and forth over the tiles until all the ones in the leash’s reach were triangles, then he stomped about in the snow. After that grew boring, he picked up a handful of snow and dropped it onto Papyrus’s back as the taller skeleton knelt over the tiles.

“SANS, PLEASE! I’M WORKING!”

Sans huffed, plopped his coccyx in the snow and crossed his arms. He was now thoroughly bored and his brother was ignoring him. After a while that got boring too, so Sans got up and ran to the end of his leash, then zigzagged around Papyrus.

Papyrus finally finished with the tile he was working on and got up to move onto the next one. When he stood he immediately lost his balance and fell face first into the snow. There was something caught around his ankles. Papyrus managed to push himself half up and get a look at what had happened: he was completely tangled up in the leash.

“SANS! WHAT DID YOU DO?!”

Sans just looked up at him with the biggest grin across his face. Papyrus sighed, then untangled himself. He did a quick check of his inventory, he had taken to keeping a couple toys in there for when he needed a quick distraction for Sans. Oh good, he had a pail and little plastic shovel set in there. “HERE SANS, WHY DON’T YOU BUILD A SNOW CASTLE?”

“okay.” Sans took the offered toys and plopped down in the snow. With a sigh of relief Papyrus returned to re-calibrating his puzzle.

“THERE, ALL RE-CALIBRATED! NOW, ONTO THE NEXT PUZZLE.” Sans didn’t resist as Papyrus picked him up and carried him over the spikes to the next puzzle. Having learned from his mistake, Papyrus decided to attach the leash to a nearby tree so Sans couldn’t tangle him up again. Though this shouldn’t take long, this puzzle was much simpler than the one he had just finished.

It turned out this puzzle had taken some damage the more complex puzzle hadn’t. Not only did Papyrus have to re-calibrate it, he had to thaw and repair it first. Eventually everything was finished and the puzzle was good as new. Papyrus dusted off his hands in satisfaction as he looked down at the puzzle. “THERE, ALL DONE! DO YOU WANT TO TRY SOLVING THIS ONE, SANS?” Papyrus turned to where he had left the toddler, “SANS?” The toddler harness was abandoned in the snow, the leash still attached to the tree. “SANS!” Papyrus ran over to the tree, little footprints led further up the path. Papyrus thanked his lucky stars that today it wasn’t snowing and the tracks were untouched.“IT’S OKAY,” Papyrus told himself as he followed the tiny little footprints, “SANS WON’T BE ABLE TO GET PAST THE SPIKES AT THE NEXT PUZZLE, HE’S TOO SMALL!”

A surge of panic welled up in Papyrus’s chest, the spikes to the next puzzle were down. It needed to be re-calibrated. And Sans’s footprints lead right through the thin layer of snow over the retracted spikes. Papyrus tried not to panic as he kept following the footprints, then a noise caught his attention. It sounded like something was whining and… snuffling? Breathing of some kind, and lots of it. He looked around the next tree and found a pile of dogs gathered around a happily squealing babybones.

“puppy!” Sans declared as he tried to pet Doggo, Dogamy, and Dogaressa all at once.

(Puppy!) Dogaressa agreed as she happily wagged her tail and sniffed at Sans’s hands.

“SANS! THERE YOU ARE! YOU HAD ME WORRIED SICK!” Papyrus ran over and picked Sans up, cuddling his babybones brother close. “DON’T EVER WANDER OFF LIKE THAT AGAIN!”

“Hello Papyrus!” The three dogs greeted as they all rolled onto their feet and got up.

Dogamy held up a paw in greeting, “Why is Sans out here?”

(… so far from town?) Dogaressa continued.

“I’M WATCHING HIM, OF COURSE!”

Dogamy and Dogaressa looked at each other, then back at Papyrus. “Make sure to keep an eye on the little pup.”

(We wouldn’t want him to get lost.)

“I KNOW,” Papyrus assured. “HE CAN BE QUITE THE SLIPPERY SNAIL SOMETIMES, BUT I AM KEEPING A VERY CAREFUL EYE SOCKET ON HIM.”

“Hmmm...” Dogamy hummed to himself, but otherwise said nothing.

Doggo pulled out a dog treat and started to light it, only to be smacked by Dogaressa. (Not near the puppy!)

“Alright, alright. Sheesh!” Doggo turned and started wandering towards his sentry station.

“WELL, I’VE GOT MORE ROUNDS TO DO AND PUZZLES TO RE-CALIBRATE.”

“We’ll see you later,” Dogamy called.

“SAY GOODBYE TO THE DOGGIES, SANS.”

“bye bye, I love you!”

There was a gasp, followed by, (“We love you too”) as Papyrus carried Sans away.

* * *

The rest of Papyrus’s shift went off without a hitch, he managed to keep Sans busy or distracted enough to not wander off again. After stopping off at home to feed Sans and grab a few more snacks and toys, Papyrus carried Sans towards Waterfall.

“gun?” Sans asked as they entered the damp caverns.

“NO, WE’RE NOT GOING TO VISIT GERSON TODAY. WE’RE GOING TO GO SEE AUNTY UNDYNE.”

“aunty!” Sans yelled happily and threw his arms up in the air.

Undyne was waiting for them outside her house, foot tapping impatiently as they entered the little nook her house was tucked in. “Papyrus,” Undyne grit out angrily.

“HELLO UNDYNE, WE’RE HERE FOR MY WARRIOR TRAINING!”

Undyne ground her teeth, “Papyrus I just… I can’t believe you!”

“I DON’T UNDERSTAND, WHAT DON’T YOU BELIEVE?” Sans started fussing as Papyrus stared at Undyne in confusion.

“I CAN’T BELIEVE YOU’D DO SOMETHING SO… SO..!” Rather than finish her sentence, Undyne yelled at the cavern roof. Sans hid his face in Papyrus’s shoulder, his bones started rattling. “You took a small child with you out into the middle of the woods while you were WORKING! And what’s more, YOU LOST HIM! Do you have any idea how lucky you are the Dogi found him?!” Papyrus tried to speak but Undyne just kept going. “What if the Dogi hadn’t found him? What if someone dangerous had? Or what if he had fallen off one of those cliffs? What would you have done if he had gotten lost in the woods and you couldn’t find him?!”

“THAT’S-”

“And then you brought him to WARRIOR TRAINING?! Papyrus! You can’t bring a toddler to warrior training! He’s a toddler for the Angel’s sake!”

“UNDYNE, YOU’RE SCARING SANS.” Papyrus ran a soothing hand up and down the trembling toddler’s spine.

“He shouldn’t even be here right now. And if you can’t get someone to take care of him for you, neither should you!”

Papyrus’s jaw opened and closed a few times, then he turned and walked away. The walk home was much slower, Papyrus kept pausing every now and then to whisper comforting words to the still trembling toddler in his arms. One of those times was next to the bridge seed puzzle, and Sans finally responded.

“aunty meeeeeeeeeaaaaaaaaan!” He wailed loudly, then burst into big, messy tears. Papyrus was relieved, if a little sad that his battle body was going to need to be washed again. The subdued trembling had stopped, and the wailing he knew how to handle. By the time they made it home Sans had quieted down to sniffles and muffled sobs that meant all Papyrus would have to do was clean him up and put on a cheerful face to distract him. Maybe put him down for a nap since he was overdue. “aunty mean,” Sans repeated once they were through the door.

“YES, UNDYNE WAS BEING QUITE FORCEFUL, BUT SHE ONLY YELLED LIKE THAT BECAUSE SHE REALLY CARES AND WAS WORRIED ABOUT YOU.”

“aunty mean,” Sans insisted angrily.

“AND SHE WON’T BE AGAIN, BECAUSE I AM GOING TO TAKE EVEN BETTER CARE OF YOU THAN BEFORE, SO SHE WON’T HAVE A REASON TO WORRY LIKE THAT AGAIN! NOW! LET’S GET YOU CLEANED UP, IT CAN’T BE COMFORTABLE HAVING YOUR SKULL COVERED IN SNOT AND DRIED TEARS!” Sans huffed, but otherwise made no fuss as Papyrus carried him upstairs to get washed up.

* * *

The next morning Papyrus walked Sans over to the Libarby, careful to keep his steps slow and small so the toddler could keep up. Inside the librarian greeted Papyrus and Sans cheerfully, “And is Sans here for the daycare?”

“YES, I WAS TOLD I COULD LEAVE HIM WITH YOU WHILE I TEND TO MY DUTIES.”

“Of course,” the librarian chirped cheerfully, “we just need you to sign him in.” The librarian pushed a clipboard over to Papyrus, which he quickly filled out.

“OKAY SANS, BE GOOD FOR THE LIBRARIANS WHILE I’M GONE.”

“no!” Sans attached himself to Papyrus’s boot and glared up at the librarian.

“SANS, PLEASE!”

“Don’t you want to play with the other children?” The librarian’s question had Sans pausing to look up at her inquisitively. “You can walk him back, a lot of children get over their separation anxiety easier when they have other children to distract them.”

“GREAT IDEA! COME ALONG SANS, LET’S GO MEET THE OTHER CHILDREN YOU WILL BE SPENDING THE DAY WITH.” Sans allowed himself to be led into the back of the library where a few other young children were already playing with toys. A curious puppy trotted over to the new comers and sniffed at Sans.

“puppy!” Sans squealed happily before enthusiastically petting the puppy.

“Pets!” The puppy happily squealed back, their tail already thrashing about. Sans was so engrossed by his new playmate that he didn’t even notice Papyrus quietly sneaking away.

When Papyrus returned to pick Sans up that afternoon, Sans dropped the toy he had been holding and ran full tilt into Papyrus’s legs. “HELLO SANS, DID YOU HAVE A GOOD DAY PLAYING WITH THE OTHER CHILDREN?”

“missed you,” Sans grumbled as he clung to his bother’s legs.

“I MISSED YOU TOO, HOW ABOUT WE GO HOME NOW?”

“ok.” Sans held his arms up, refusing to budge until Papyrus picked him up.

“Don’t forget your drawings,” one of the librarians called as she held out a few papers to Papyrus.

“OH! I CAN’T WAIT TO LOOK AT THESE! I’LL PUT THEM RIGHT UP ON THE FRIDGE.” A big, excited grin was plastered over Papyrus’s face as he accepted the drawings.

Sans smiled bashfully and leaned his head against his brother’s shoulder, “love you, pappus.”

“I LOVE YOU TOO, SANS.” Papyrus dropped a kiss on top of Sans’s skull as they left the library.

Once home Sans refused to be put down, so Papyrus simply settled on the couch with Sans in his lap as he began looking through the drawings Sans had made. The first one was a lot of black shapes scribbled all over the page.

“WHAT’S THIS?”

“a bastard!” Sans replied as he pointed to one of the empty spots the black was scribbled around.

“A… A BASTARD?” Papyrus asked in disbelief.

“yeah! it goes bweeeeeeeen!” Sans held his hand up to his teeth and made a “roar” motion.

Papyrus looked back at the drawing, if the black were background and not the drawing itself like Papyrus had originally assumed… “OH, A BLASTER! YOU MEAN OUR SPECIAL ATTACK.” Papyrus summoned a blaster to illustrate his point.

Sans clapped his hands and pointed at the large skull floating serenely in the living room, “bastard! bastard!”

Papyrus dispelled the attack before an accident could happen, it was never wise to summon attacks indoors after all. “IT’S PRONOUNCED ‘BLASTER’, SANS. BLA-STER.”

“baster.”

“GETTING CLOSER.” He flipped to the next drawing, it was three faces. He could tell one was him and one was Sans, which meant the third one must be their father. Since it was just their faces this time there were more details, like uneven pupils inside their father’s eyes. Then again, the pupils Sans drew for his own eyes weren’t even either, it was likely just due to his toddlery hand-eye coordination. Aside from the pupils and what Papyrus could only assume was a pair of square-ish glasses, their father’s face looked very similar to his own, right down to the exaggerated cheekbones Sans had given them both.

“thaz you an’ me an’ daddy!” Sans cheerfully explained as he pointed to the faces.

“I CAN TELL, YOU DREW US VERY WELL.” The next drawing was their father again, this time alone. A full body picture that had their father wearing a long, white coat with dark clothes under it and some sort of square thing in on hand. “AND THIS IS DADDY TOO, RIGHT?”

“yeah!” Sans said excitedly. “when daddy come home?”

“I… I DON’T KNOW.” Papyrus admitted sadly. He really wished he could remember their father, or what had happened to him. Papyrus flipped to the next drawing, the first one to actually have any color in it. “OH! IT’S ME! AND MY BATTLE BODY!”

“yeah!” Sans grinned up at Papyrus.

The older skeleton felt tears welling up in his eye sockets, “THIS IS THE MOST BEAUTIFUL DRAWING I’VE EVER SEEN! I’M GOING TO GET THIS FRAMED!” Papyrus hugged Sans, which the toddler returned while giggling. After they had a moment to calm down, Papyrus flipped to the last picture. “IS THIS GRILLBY?”

“girby!”

The picture featured an orange, vaguely flame shaped blob with a few black shapes below it that could be Grillby’s usual vest and bow tie if you turned your head and squinted. “WE’LL HAVE TO SHOW THIS TO GRILLBY NEXT TIME WE SEE HIM, I’M SURE HE’LL BE VERY FLATTERED.”

“girby,” Sans said again, more quietly this time.

Papyrus picked Sans up and walked into the kitchen, “IN THE MEANTIME, LET’S PUT THESE ALL UP ON THE FRIDGE.” It was already overflowing with the drawings Sans had made, but Papyrus couldn’t bear the thought of taking any of them down. He shuffled the drawings around until there was room for the new ones, which were promptly put on display. “THERE! NOW, WHO’S READY FOR DINNER?”

“dinner!” Sans repeated and threw his hands into the air.

**Notes for the Chapter:**

> This chapter has some of my favorite lines, including my all fic favorite: bastard! I love it so much! I just... I’m so glad I came up with that. *wipes a tear away*


	4. The Aftermath

**Summary for the Chapter:**

> The new, new routine gets interrupted, Alphys gets paid a visit, Grillby gets begged for help, Sans is still mad at Undyne, and then things get resolved. Mostly.

Papyrus found his life falling into a new rhythm: dropping Sans off at the Librarby in the morning, going about his sentry duties, warrior training with Undyne, then rushing back to Snowdin to pick Sans back up before the Librarby daycare closed for the day. But then his first day off since going back to work rolled around and Papyrus found himself agitated. Sans was delighted, as much fun as he had with the other children he still never got over his anxiety at being separated from his brother. And Papyrus had to admit that it was nice to spend more time with Sans today too, but something was nagging at him…

He hadn’t heard from Alphys again. It had been nearly two weeks since Sans was turned into a toddler, surely that was enough time to translate all the notes at least, right? And Alphys had said she was going to keep him updated, but he still hadn’t heard a peep from her except for the one call that he had started. Well, perhaps a friendly visit was in order. After all Alphys and Sans were friends too, right? Papyrus filled his inventory with snacks and toys for Sans, although he wasn’t going to let the toddler out of his sight in the Lab. He was pretty sure it would be a bad idea to let Sans wander around in there, but it was best to be prepared.

It took until the third knock for Alphys to answer the door, but when she did she sure had a surprise. “Oh! Papyrus! And Sans!”

“HELLO, DR. ALPHYS! WE CAME BY FOR A VISIT.”

“ally!” Sans yelled and reached for Alphys, she obligingly leaned forward.

“H-hello Sans, how are yo-” Her sentence was cut off when Sans bapped her nose. Alphys leaned back in surprise, then smiled and blushed. “H-he’s so cute!”

“YES, SANS IS VERY FRIENDLY. BUT HE IS ALSO VERY SHY?? TRULY, MY BROTHER IS FULL OF CONTRADICTIONS NO MATTER HIS AGE.”

“Well come in, y-you wanted to know how I’m doing with the machine, r-right?”

“I WILL ADMIT TO HAVING ULTERIOR MOTIVES TO THIS UNPLANNED FRIENDLY VISIT,” Papyrus cheerfully admitted as he followed Alphys into the Lab.

“I kn-know you said you didn’t know any uh… any codes or ciphers, but if you want you can l-look at what I’ve got so far. I’m almost done with the last page.” Alphys led them over to her desk, where she blushed as her eyes landed on the massive stacks of empty noodle bowls. “D-don’t mind the mess. I was uh… I can get pretty single minded sometimes.” She quickly gathered up the papers and handed them to Papyrus.

“HERE, HOLD SANS PLEASE,” Papyrus skillfully handed the toddler off to Alphys as he began flipping through the papers.

“Wh-w-what do I do?!” Alphys asked in a panic as Sans settled into her arms.

Sans immediately started touching her face and giggling. “feel funny!”

“Heh, I suppose uh… I guess my face would feel funny. Scales are r-really different than bone.”

“HIS HANDWRITING IS JUST AS MESSY AS EVER,” Papyrus commented absently as he shook his head.

“W-whose handwriting? What?”

“WHAT?”

“You s-said ‘his handwriting is just as messy as ever’ so uh… whose h-handwriting? Do you recognize it?”

Papyrus blinked, then looked back down at the papers, then up at Alphys again. “I DO, ACTUALLY, BUT I CAN’T REMEMBER WHOSE OR FROM WHERE.”

Alphys sighed, “Sans wouldn’t talk about it either.”

“I REALLY DON’T REMEMBER,” Papyrus insisted. “IT’S BEEN… SO FRUSTRATING. THERE ARE HOLES IN MY MEMORY I DIDN’T EVEN REALIZE WERE THERE UNTIL AFTER UH… YOU KNOW.”

“R-right… the accident.”

Papyrus flipped through more papers. “WOW, I CAN’T EVEN READ THESE!”

“Th-that’s uh… those’re mine.” Alphys hid her face behind Sans, who giggled and squirmed in response.

Papyrus flipped back to the original notes, “SO IT LOOKS LIKE IT WAS SUPPOSED TO BE A TIME MACHINE OF SOME KIND?”

“You can tell?!”

“YES??? I MEAN… ISN’T IT OBVIOUS?”

“Did I translate everything right? And the numbers! It’s harder to decode numbers because unlike words there’s no easy way to recognize it without a constant like writing out the digits of pi or something.”

“I HONESTLY CANNOT READ YOUR HANDWRITING.”

“W-well maybe it’d be better if you just translated it yourself. Wait.” Alphys shoved Sans back into Papyrus’s arms and rushed over to her desk. She scrambled about the desk, causing a noodle bowl avalanche, then turned back and held up an armful of paper and pens. “Here! If you could just write everything! A-and if you’re familiar with the machine you could also help me repair it!”

“ALPHYS, WHILE I AM HAPPY TO HELP YOU IN ANY WAY I CAN, I DON’T THINK IT’S A GOOD IDEA TO JUST JUMP IN LIKE THIS. I MEAN… WHAT WOULD WE DO WITH SANS? I DON’T THINK IT’S A GOOD IDEA TO LET HIM WANDER AROUND YOUR LAB. IF UNDYNE FOUND OUT...”

“aunty mean,” Sans groused and clung tighter to Papyrus.

“At least take these home and work on them. And after that’s d-done then maybe you can get a babysitter? Oh! I bet Undyne would wa-”

“aunty mean!” Sans insisted even louder and glared with all the hate his little toddler body could muster.

“I DON’T THINK SANS WOULD LET HER, HE SEEMS TO STILL BE MAD AT HER FOR GETTING MAD AT ME.”

“I r-remember that, she was pretty upset.” There was an awkward pause as they both stared at each other. “W-well here, take these and translate everything for me at least.”

Papyrus leaned down and sat Sans on the floor. “SANS, STAY HERE FOR A MINUTE PLEASE. DO NOT GO WANDERING OFF.” That take care of, he pulled a snack out of his inventory, opened it up, and handed it to Sans. With a space opened up, he gathered all the papers and pens into a single, neat pile and tucked it away in his inventory. “ALRIGHT, DR. ALPHYS, I’LL TRANSLATE EVERYTHING FOR YOU. AND SEE IF I CAN FIND A BABYSITTER FOR SANS. THE WORK WILL HAVE TO BE BETWEEN MY SENTRY SHIFTS, I’M NOT GOING TO LET UNDYNE DOWN AGAIN.”

“No, that’s great. I’ll t-talk to Undyne and get y-your shift schedule, then I’ll contact you through Undernet an-and we’ll work out a schedule. Oh! I should friend you, it’ll make working this out all the easier.

“THAT SOUNDS LIKE AN EXCELLENT PLAN.” Papyrus hid his glee by bending down to pick Sans back up. Another friend successfully made by the Great Papyrus! “GOODNESS, SANS! HOW DID YOU GET SO MESSY SO FAST?” He wiped the crumbs off Sans’s face and from between his finger joints, then looked down at the mess of crumbs left on the floor.

“D-don’t worry about that, I sh-should clean up around here anyway.” Alphys glanced at the noodle bowl avalanche cascading down her desk and flinched.

“WELL, IF YOU ARE SURE… THEN I WILL SEE YOU LATER, DR. ALPHYS. SAY GOODBYE, SANS.”

“bye bye,” Sans waved at Alphys, “i love you.”

Alphys waved back, her face turning a brilliant shade of red as the skeletons left the Lab.

* * *

Finding a babysitter for Sans was turning out to be harder than Papyrus first anticipated. While there were several people more than willing to watch Sans, there were very few people Sans was willing to be separated from Papyrus for. In fact, so far there seemed to be none. Sans threw a fit each and every time, even for the Dogi. Papyrus had hoped Ruby or Sylvila could help, they both had children of their own and that seemed to help Sans with the daycare, but that didn’t pan out. Thus Papyrus found himself back in the den of grease, desperately trying to keep an active toddler from climbing up onto the bar as he talked to Grillby.

“PLEASE, GRILLBY. YOU’RE REALLY GOOD FRIENDS WITH SANS, RIGHT? AND HE TRUSTS YOU, EVEN AS A LITTLE TODDLER. HONESTLY, HE DOESN’T SEEM TO TRUST ANYONE ELSE AS MUCH AS HE TRUSTS YOU, EXCEPT FOR ME OF COURSE. AND I TRUST YOU WITH HIM TOO.”

“………… the bar is no place for a small child.”

Sans grunted and squirmed in his brother’s grasp, “girby!”

“I CERTAINLY WOULDN’T EXPECT YOU TO WATCH HIM HERE, YOU COULD COME OVER TO OUR HOUSE. I JUST NEED SOMEONE TO WATCH HIM IN THE EVENING WHILE I HELP DR. ALPHYS REPAIR THE MACHINE THAT STARTED THIS WHOLE MESS. HOPEFULLY IN A FEW DAYS SANS WILL BE BACK TO NORMAL AND WE CAN PUT ALL THIS BEHIND US.”

“…….. I need to run the bar.”

“YOU HAVE EMPLOYEES, DON’T YOU? PLEASE GRILLBY, I’VE ALREADY TRIED ASKING EVERYONE ELSE, I REALLY HAVE.”

Grillby sighed, then set aside the pitcher he had been polishing and held his arms out. Sans gave one great heave out of Papyrus’s grasp and ran into Grillby’s arms.

“SO IS THAT A YES?”

Sans happily settled himself against Grillby’s chest, followed shortly by a soft popping sound. Then another, then a flurry of them.

“SANS! HAVE YOU BEEN SHOVING THINGS IN YOUR ORBITS AGAIN?” Grillby looked down in surprise, a piece of popcorn hopped out of one of Sans’s orbits. The toddler simply grinned up at the bartender. “TAKE EVERYTHING OUT OF YOUR ORBITS RIGHT NOW, YOUNG MAN!”

Grillby watched in horror as Sans shoved a hand into one of his eye sockets, his tiny fist came out clutching some popcorn mixed with a few kernels. Sans looked down at his fist full of half popped corn, then shoved the whole thing in his mouth.

“SANS!” Papyrus scolded.

Grillby put a hand under Sans’s chin, causing the popping to increase. Sans squealed in delight as more popcorn started hopping out of his orbits.

“GRILLBY, DO NOT ENCOURAGE THE TODDLER, PLEASE!”

“…… I will watch him for you.”

“OH! THANK YOU, MR. GRILLBY! I REALLY APPRECIATE IT!” Papyrus reached for Sans, who whined and cuddled further into Grillby’s hold. Grillby made no move to hand Sans over. “MR. GRILLBY, I NEED SANS BACK NOW.”

Grillby reluctantly held Sans out to Papyrus. Sans burst into tears and started wailing as he scrambled to keep ahold of Grillby’s sleeves. Everyone in the bar flinched at the volume.

“SANS PLEASE, YOU’LL SEE MR. GRILLBY LATER. HE ALREADY SAID HE WAS GOING TO WATCH YOU WHILE I HELP DR. ALPHYS WITH HER MACHINE.” Sans wailed louder as he was carried towards the door. “I’M VERY SORRY ABOUT THIS,” Papyrus said contritely before quickly walking out of the bar.

* * *

It was the next night that everything was set in motion, after a long day of patrolling followed by warrior training with Undyne, Papyrus picked up Sans from the Librarby like normal, took him home and cared for him like normal. They had just finished cleaning up dinner and were about to lay on the floor with blank paper and crayons when there was a knock at the door. Papyrus left Sans with his drawing supplies to go answer the knock.

“…………… good evening.”

“HELLO MR. GRILLBY, COME RIGHT ON IN.”

As Grillby entered there was a shriek in the living room, Sans scrambled to his feet and started running, he managed two steps before he fell flat on his face. Grillby looked ready to rush over, but Sans was already back on his feet and running across the room to latch himself onto Grillby’s legs.

“girby!” Sans happily squealed.

“…… hello, Sans.” Grillby reached down and picked Sans up, more to keep himself from tripping over the toddler than anything else.

“SO WE JUST FINISHED DINNER, BUT I LEFT SOME SNACKS OUT ON THE COUNTER IN CASE HE GETS HUNGRY BEFORE BED. WE WERE JUST ABOUT TO START DRAWING, THAT SHOULD KEEP HIM OCCUPIED FOR A WHILE. THERE’S A BOX OF TOYS IN THE CORNER IF THAT’S NOT ENOUGH. OH! AND I USUALLY GIVE HIM A BATH BEFORE BED, BUT YOU DON’T HAVE TO IF THAT’S NOT SAFE.”

Grillby held up a hand, “……… I own a restaurant, water is no problem.”

“OKAY THEN. SANS, BE GOOD FOR MR. GRILLBY WHILE I’M GONE.” He leaned down and kissed Sans on the skull. “I’LL BE BACK IN A FEW HOURS.” Sans gave a faint whine as Papyrus left, but happily settled into Grillby’s arms when he started petting his skull.

The trip to Alphys’s Lab was quick and uneventful, he walked through the doors and cheerily called out, “HELLO, DR. ALPHYS! I HAVE ARRIVED!”

“Hello P-Papyrus, do you have the notes?”

Papyrus pulled a folder from his inventory and handed it over. “OF COURSE I DO, EVERYTHING HAS ALREADY BEEN COPIED OVER AND ACCURATELY TRANSLATED. THOUGH I WAS SORELY TEMPTED TO MAKE A FEW CORRECTIONS, WHO IN THEIR RIGHT MIND WOULD DESIGN A KILL SWITCH TO BE ON THE BACK OF A MACHINE?”

“Right?!” Alphys asked as she opened the folder and started leafing through. “Oh wow! You even copied over the drawings, and they’re so well done!” Papyrus preened at the praise. “Well, I should p-probably show you the machine. It’s downstairs in uh… in storage.” She lead Papyrus over to the elevator and took him down to one of the lower floors. The machine in question was one of several around the room in various stages of disrepair. The one they were looking at was the most whole of the bunch, something that had actually been finished and even cared for at one point. Papyrus looked it over with a critical eye.

“WOWIE, WHAT SHODDY WORKMANSHIP! IT’S A WONDER THIS FRAME HASN’T CRUMPLED IN ON ITSELF.”

“I th-thought the same thing! If you look inside you can see where they reinforced the frame, but it interferes with the access panels to the innards and… well… just w-wait until you see the wiring harness,” she concluded in disgust.

“I DON’T THINK I REALLY WANT TO, BUT THE SOONER WE START THE SOONER WE CAN HAVE SANS BACK. I HAVE FAR MORE QUESTIONS FOR HIM THAN I DID WHEN THIS WHOLE THING STARTED.”

“Y-yea, I think we all do.”

* * *

It was several hours later that Papyrus went home. They had gotten a lot done, between Papyrus’s translations and the strange familiarity of the design, the worst of the damage had been repaired that evening. Alphys was already talking about figuring out how to do a test run, what would make the best test subject, and recreating the accident without damaging the machine again. Papyrus felt better about that, he’d like to test the machine before putting Sans back in it.

Papyrus opened the door to find Grillby sitting on the couch with Sans curled up in his lap. Sans had already been changed into pajamas: a onesie covered in stripes with a pair of triangular ears attached to a hood and a long tail attached to the back. Grillby raised a finger to his face, the other hand slowly petting sans like a puppy. Papyrus softly shut the door and walked quietly over to the couch.

“GOOD EVENING, MR. GRILLBY,” Papyrus said softly.

“…………… I wasn’t sure where to lay him down,” Grillby replied just as softly.

“I CAN TAKE IT FROM HERE, THANK YOU AGAIN FOR WATCHING SANS.”

“……… how did repairs go?”

Papyrus picked Sans up, the toddler squirmed for a moment, then settled sleepily into his brother’s arms. “VERY WELL, WE HOPE TO DO A TEST RUN BY TOMORROW, THE NEXT DAY AT THE LATEST.” Grillby nodded, then stood up and gave a wave before heading out of the house.

* * *

Two days later Papyrus, Sans, Undyne, and Alphys were all gathered at the Lab. The machine had been moved up to the ground floor and the quartet were all gathered around it.

“So you’re just gonna… stick Sans in that thing and presto! He’s himself again?” Undyne asked as she looked at the thing skeptically. Sans was glaring at her from his spot cuddled up in Papyrus’s arms.

“Papyrus should probably un-undress him first.” When Undyne gave her a look, Alphys continued, “I-if uh… _when_ this works the clothes he’s in now will uh… they’ll be too small.”

“I REALIZED THIS AND CAME PREPARED,” Papyrus announced as he held up the outfit Sans had been wearing the day of the accident.

“Okay! Let’s turn this toddler back into an adult!” Undyne raised a fist in the air in excitement while Papyrus carefully undressed Sans, then wrapped him in his faded blue hoodie.

“OKAY SANS, WE JUST NEED YOU TO SIT RIGHT HERE FOR A MINUTE. I KNOW IT MIGHT BE A LITTLE SCARY, BUT NOTHING WILL HURT YOU, I PROMISE.”

“you promise?” Sans asked in a wavering voice.

“YES, I PROMISE. EVERYTHING’S GOING TO BE JUST FINE.” Papyrus shut the door, then stepped back and started wringing his hands. Alphys was already waiting at the control panel they had migrated to the outside of the machine, she pressed the start button. The machine made a strange, keening noise for half a minute, then suddenly stopped with a puff of smoke. Papyrus rushed back to it and yanked the door open. “SANS! ARE YOU OKAY?”

There was coughing coming from the now open door. “yeah, i’m fine… paps? what’re you doing he- where’re my clothes?! what happened?!”

Papyrus turned to the rest of the room with a giant grin on his face. “GIVE US JUST A MOMENT, PLEASE.”

“Yeah, no problem. I don’t want to see a grown naked skeleton running around anyway.” Undyne shuddered at the thought while Alphys hid a laugh behind her hands. After a minute, Papyrus led a still wobbly but fully dressed Sans out of the machine and into the rest of the lab.

“okay, so is anyone going to explain what happened or...” Sans trailed off as his pupils settled on Undyne. “whoa, okay… what happened? why am i so mad at Undyne?”

Undyne’s grin only spread further, “You’re angry at me?”

“yeah it’s like… i really just want to punch you right now but i have no idea why.”

“Wow, I knew he was holding a grudge as a toddler but I didn’t think he’d keep holding it after growing up, that’s hilarious!” Undyne started laughing and banging a hand against her knee.

“toddler?”

“Th-there was an accident with the machine we were inspecting and uh… you got turned into a toddler.”

“okay...” Sans trailed off as he looked around. “that’s really weird.”

“IT WAS SUPPOSED TO BE A TIME MACHINE BUT WE DON’T THINK IT EVER WORKED PROPERLY.”

“how long?”

“Two weeks!” Undyne answered gleefully.

“wow, okay, that’s a long time to be stuck as a little kid and have absolutely no memory of it. is anyone gonna tell me why little toddler me was so angry at undyne?”

“I got mad at your brother and yelled at him in front of you.” Sans turned a glare on Undyne. “Oh come off it, that was a week ago now.”

“I… MAY HAVE DESERVED IT. I WAS NOT THE BEST CAREGIVER FOR YOU WHILE YOU WERE A TODDLER.”

“aw, no. i’m sure you were the best, bro, you always are.”

“I DID IMPROVE VASTLY AS TIME WENT ON. BUT I AM ALSO GLAD THAT I DON’T HAVE TO ANYMORE BECAUSE YOU’RE YOU AGAIN.”

“I’m glad too,” Alphys said. “It’s great to have this whole mess cleaned up, I th-think I’ll take this thing apart too. J-just to make sure this never happens again. Plus I c-can always use the parts for something else.”

“I’m just glad to finally have all my sentries back, you know how hard it is to replace you?”

“heh, yeah, i’m irreplaceable.”

Papyrus lunged forward and picked Sans up in a hug that he had been holding back since Sans had returned to normal. “I MISSED YOU SO MUCH, BROTHER! WHICH IS ODD BECAUSE YOU WERE HERE THE WHOLE TIME, JUST SMALLER THAN USUAL.”

“heh, ilove you too, bro.” Alphys and Undyne both snorted and turned away as Papyrus set Sans down. Sans looked at them with a quirked brow, but neither seemed willing to tell him what that was about.

“LET US GO HOME! I’M SURE AFTER ALL YOU’VE BEEN THROUGH YOU COULD USE THE FAMILIAR SURROUNDINGS.”

“yeah, sounds good paps. see you two later.”

“Bye bye!” Alphys called as she waved, Undyne snorted and turned away. Sans raised a brow again, but chose to drop it in favor of following his brother home.

Walking into the house was strange, Sans looked around the living room to see a few toys strewn about here and there, and a cardboard box full of more sitting next to the couch. The toys seemed… vaguely familiar somehow. Sans picked up a bright orange dinosaur left in the middle of the floor.

“so uh… this mine?” Sans asked as he turned the toy over in his hands.

“YES, ALL OF OUR NEIGHBORS WERE VERY KIND AND DONATED CLOTHES AND TOYS TO USE UNTIL YOU WERE RETURNED TO YOUR REGULAR, ALBEIT STILL DIMINUTIVE, STATURE.”

“that was really sweet of them.” Sans tossed the toy in the general direction of the box, then headed for the kitchen. “being turned from a kid to an adult must really do something to ya, i’m feeling half starved.” Sans stopped cold on entering the kitchen and stared at the refrigerator. “papyrus, what’s all this?”

Papyrus stepped into the kitchen and looked at the fridge. “THOSE ARE ALL THE DRAWING YOU DID. YOU DREW A LOT, IT WAS AN EASY WAY TO KEEP YOU BUSY.”

“yeah, guess that makes sense.” Sans started looking through the drawings, lifting the ones in front to look at the layer underneath and moving them around. Most of the drawing were oddly shaped scribbles that he couldn’t make out, but one caught his eye. He pulled it off and stared down at it.

Papyrus leaned over his shoulder to see what he was looking at. “OH, THAT ONE’S A FAMILY PORTRAIT.” He pointed to each smiling face as he explained the picture. “THAT’S YOU, THAT’S ME, AND THAT’S OUR FATHER.”

“i… remembered dad?” Sans’s hand started to tremble.

Papyrus nodded, “IT WAS HARD TRYING TO EXPLAIN TO A TODDLER WHY HE WASN’T STILL AROUND WHEN I DON’T REMEMBER HIM MYSELF. SANS, WHAT HAPPENED?”

“i don’t… i don’t know either.” Sans sighed and stuffed the picture into a pocket. “whatever happened it messed with our memories, that’s about all i ever figured out.”

“OH...” Papyrus trailed off. “WELL IF YOU’RE HUNGRY YOU SHOULD EAT SOMETHING, THE NEIGHBORS ALSO GAVE US MORE FOOD THAN I KNEW WHAT TO DO WITH. THERE’LL BE NO NEED FOR EATING OUT FOR QUITE SOME TIME!”

“awww… but i wanted to stop by grillby’s later and tell everyone i’m back. i’m sure they all missed me.”

Papyrus nodded, “THEY DID, AND YOU SHOULD PROBABLY GO SAY ‘HELLO’ YOURSELF IF NOTHING ELSE. AND THANK GRILLBY FOR WATCHING YOU WHILE YOU WERE SMALL.”

Sans’s pupils blinked out of existence. “what?”

“WELL SOMEBODY HAD TO WATCH YOU WHILE I HELPED DR. ALPHYS REPAIR THE MACHINE, AND YOU THREW A FIT EVERY TIME I TRIED TO LEAVE YOU WITH ANYONE ELSE. HONESTLY, YOU WERE AN INCREDIBLY CLINGY LITTLE CHILD.”

Sans flopped into a kitchen chair and dropped his skull into his hands. “oh my god!”

Papyrus gasped, “YOU SHOULD SEE THE PICTURES!”

“oh my god!!” Sans moaned.

Papyrus hummed and moved about the kitchen as Sans continued to cradle his skull in his hands. After a few minutes, Papyrus set a plate of warmed cheesy macaroni casserole in front of Sans.

Sans looked up, “what’s this?”

“YOU SAID YOU WERE HUNGRY, AND IT’S LUNCH TIME ANYWAY.” Papyrus sat down with his own plate and started eating.

Sans sat up, then frowned as something rattled in his skull at the movement. “is there something in my orbit?” He dug his fingers in and came out with a large pebble.

“UGH, EVERY TIME I TOOK MY EYE SOCKETS OFF YOU I SWEAR YOU WERE SHOVING SOMETHING ELSE IN YOUR ORBITS. I HAD TO PULL A WHOLE POTATO OUT ONCE.”

“a whole potato?” Sans asked skeptically. Papyrus just nodded, his mouth full of cheesy noodles. Sans dropped his skull back into his hands. “two weeks of running around as a toddler and i don’t even remember any of it.”

“I’LL SHOW YOU THE PICTURES AFTER WE EAT, I’VE BEEN POSTING THEM TO MY BLOG.” Sans groaned again. “EAT YOUR LUNCH, SANS,” Papyrus ordered in a stern voice.

Sans didn’t look up, but he at least put a forkful in his mouth. “hey, this is pretty good.”

“BONNIE MADE IT. ONE OF THE FEW THINGS I COULD GET YOU TO EAT THAT WASN’T PRE-PACKAGED SNACK FOOD.”

“what, like i was a fussy little kid?”

Papyrus tolled his eye sockets. “YOU HAVE NO IDEA!”

That got a laugh out of Sans, the rest didn’t seem so bad after hearing that. He took another bite of lunch, “so explain to me exactly what happened with undyne, i really wanna hear the whole story.”

“WELL, IF YOU REALLY MUST KNOW I SUPPOSE I WILL HAVE TO TELL YOU.” They spent the rest of lunch with Papyrus telling Sans about his day going on patrol as a toddler and Undyne’s subsequent chewing out. “IN MY DEFENSE,” Papyrus concluded as he gathered up the dishes, “NO ONE TOLD ME THERE IS A DAYCARE FOR SMALL CHILDREN IN THE SNOWDIN LIBRARY.”

“there’s a daycare in the librarby?”

“YOU KNOW VERY WELL IT’S CALLED A LIBRARY, SANS! AND YES, I DROPPED YOU OFF THERE BEFORE PATROL EVERY MORNING. THERE IS A PUPPY THERE YOU WOULD RUN TO GO PET FIRST THING, IT WAS RATHER ADORABLE.” Papyrus paused, then turned his brilliant grin on Sans. “I GOT PICTURES! THEY’RE UP ON MY BLOG, AS I ALREADY SAID, SO YOU CAN GO FIND THEM YOURSELF OR I CAN SHOW THEM TO YOU AFTER I FINISH THE DISHES.”

“whatever makes you happy, paps.”

After Papyrus finished washing up, he led Sans up to his room. Sans looked around, the room was mostly unchanged, the only notable difference was the complete lack of action figures in sight. In their spot was now another cardboard box full of toddler friendly toys and beside that lots of very tiny clothes laid out in neat piles. Sans stared at the piles of clothes as Papyrus rambled on. “… AND THE DOGI SEEMED ESPECIALLY FOND OF YOU. DOGARESSA EVEN ADMITTED TO ME THAT DOGAMY SUGGESTED THEY HAVE A PUPPY OF THEIR OWN SOON. AND… SANS? ARE YOU OKAY?”

“i’m fine. it’s just… kinda weird looking at all this stuff. it’s almost familiar but i can’t remember how or why.” Sans picked up a tiny sock, then let it drop back with the rest.

“I SUPPOSE SINCE WE DON’T NEED THEM ANYMORE I SHOULD PACK ALL THESE UP AND GET RID OF THEM. MAYBE FIND OUT IF ANY OF OUR NEIGHBORS COULD USE THEM, SINCE THEY ALL GAVE THIS TO US.”

“yeah, there’s always someone with a kid that needs more socks.”

“AND IT’LL BE NICE TO FINALLY HAVE MY ROOM TO MYSELF AGAIN, I HAD TO HIDE MY ACTION FIGURES. YOU KEPT SHOVING THEM IN YOUR ORBITS!” Papyrus glared at Sans.

“what can i say? you have the coolest action figures.”

“I REALLY DO, NYEH HEH HEH.”

After being thoroughly embarrassed by seeing the pictures of himself as a toddler, and don’t think Sans didn’t notice he was tagged in every one, Sans finally made it to his room. He needed a break just to absorb everything after the day he’d had so far. He opened the door and stared in shock: his room was clean! It happened once in a while, when Papyrus couldn’t stand the mess anymore and bullied Sans into cleaning with him. Sans didn’t mind it so much when Papyrus helped, it was like brotherly bonding time. But this had happened without Sans around to watch, from his point of view it had happened in just the few hours he was gone helping Alphys with her organizing. It was just another mark on the weird tally that he didn’t know how to deal with.

“hey paps, ‘m gonna head on over to grillby’s and let everyone know i’m back.”

“HAVE FUN, AND BE HOME FOR DINNER. WE HAVE PLENTY OF FOOD IN THE HOUSE, EVEN IF IT ISN’T MY AMAZING COOKING.”

“alright paps, see you later.” Sans strolled out the house, his slippers squelching satisfyingly in the wet snow. Several townsfolk waved as he passed, Sans waved back cheerfully. He wasn’t sure what to expect when he opened the door, but it was Grillby’s. Nothing could have changed in the last two weeks, right? Sans took a deep breath before opening the door and walking in, “hey everyone.”

“Sans!” “Hey, it’s Sans!” “Hi, Sansy!” The other regulars all yelled their greetings at Sans, the dogs were wagging their tales a mile a minute, and Sans couldn’t be sure but he thought he saw Grillby go through several different shades of yellow and white when he first walked in. Sans did his usual round of greetings before taking his usual seat at the bar.

Grillby walked up and leaned over the bar, “……… good to have you back.”

“good to be back, i guess. can’t say i remember much of the last two weeks, heard you watched me?”

Grillby nodded, his face as unreadable as ever. “……… babysat you while Papyrus helped Alphys.”

“It’s hard to believe how loud you were as a kid,” Red cut in with a chortle.

“oh yeah?” Sans asked with interest. “what? paps brought me in here and i kicked up a fuss or something?”

“Yeah,” Red answered. “Papyrus brought you by a couple times. You always wailed at the top of your lungs when it was time to go.”

Sans’s face fell at Red’s words, he hadn’t expected his joke to turn out to be reality. “i didn’t want to go?”

“More like you didn’t want to let go,” Red chuckled as they motioned to Grillby, who was still leaning over the bar towards Sans.

“…… I would say the whole experience was very enlightening. I think I learned a lot about you… Sans.”

“what uh...” Sans swallowed nervously despite not having a throat. “what’d i do?” Red chuckled, but otherwise kept quiet and let Grillby tell this part of the story.

“……… every time you saw me,” Grillby started, and Sans swore he saw a grin on the elemental’s blank face, “you did everything in your power to get close. And when Papyrus pulled you away...” Sans felt his face flush as Grillby paused, “you cried like the whole world was ending.”

“i cried?” Sans repeated back, unsure if he really wanted to hear more.

“Total toddler meltdown,” Red added with a snicker. Sans pulled his hood up and slouched down in his seat, if only the earth would open up and swallow him whole! There were titters coming from the corners of the restaurant, but Sans chose to ignore them.

“…………… you were a very affectionate little child.”

Sans groaned and dropped his head on the bar. “i don’t want to hear any more!”

“……… at least tell me you don’t have any more popcorn in your eyes.”

Sans sat up, “welp, it was great catching up with you guys, but i promised paps i wouldn’t stay out late tonight.”

“It’s not even three o’clock yet,” Red protested.

“it’s been fun, i’ll be around.” Sans waved to the room as he slipped off his stool and headed for the door.

As if on cue, the entire bar called, “Bye bye, I love you,” to Sans.

He froze, then turned to look back into the restaurant. Every single patron had huge grins across their faces, the dogs were wagging their tails even faster than when he had entered, Grillby was waving his fingers at Sans. Sans’s mind stuttered, and when it finally found its footing again he pulled his hood even further over his face, then pulled the drawstrings until there was nothing left of his face showing. Somehow he found the door through that and hunched his way out of the restaurant.

Once safely back home, Sans flopped onto the couch and fell sideways, his hood still scrunched up around his face. Papyrus was picking up the box of toys when Sans came in, but that was abandoned when Papyrus saw Sans’s distress. “SANS, WHAT HAPPENED?”

“we gotta move, bro.”

“WHAT? WHY? TELL ME WHAT HAPPENED!”

“we just gotta! i can never show my face in snowdin again.”

“SANS,” Papyrus moved to sit on the couch next to his brother. “ARE YOU GOING TO TELL ME WHAT HAPPENED OR IS THIS GOING TO BE ANOTHER POINTLESS SECRET?”

“apparently i was a ‘very affectionate’ kid.”

“WELL, YES. YOU SEEMED TO THINK ‘I LOVE YOU’ WAS JUST HOW YOU SAID GOODBYE.” Sans groaned and buried his face into the couch cushions. “YOU WERE ALSO VERY CLINGY AND DIDN’T LIKE TO BE SEPARATED FROM ME OR GRILLBY.”

“red called it a ‘total toddler meltdown’.”

“A VERY APT DESCRIPTION. BUT I THOUGHT IT WAS VERY SWEET, EVEN WITHOUT REMEMBERING US IT WAS VERY CLEAR YOU STILL CARED VERY DEEPLY FOR YOUR GOOD FRIEND AND YOUR COOL BROTHER.”

“yeah… you are the coolest.”

“AND EVERYONE UNDERSTANDS THAT YOU COULD NOT HELP HOW YOU ACTED AS A TODDLER, SMALL CHILDREN ARE KNOWN FOR BEING EMOTIONAL AND IRRATIONAL AFTER ALL.”

“yeah, but it doesn't stop them from teasing me about it.”

“THAT WILL EVENTUALLY PASS. SO STOP BEING SUCH A BABYBONES ABOUT IT.”

Sans groaned and buried his face even deeper into the couch.

**Notes for the Chapter:**

> Tada! I hope everyone had as much fun reading this fic as I did writing. And let me tell you! It was fun to write! Or at least the concept was fun to bat around with Skerb. I know I left it pretty open, especially with all the Gaster stuff, but I honestly did no intend to write that. Hopefully I can address it later, possibly in a different fic. Some headcanons just span across a writer's work and this might be one of them. I do also have a couple ideas related to this fic I'd love to explore, but mostly I want to get back to working on the other stuff I have going. It'll be nice to have my inspiration not wrenched bodily in weird directions again... hopefully.


End file.
